I hope you will mash!
Guess I'll make this my progress post.
Tried my first two quick sketches of the house (and a small try at a swing set design):

They're taking the 'rundown' description quite far, but I'm a sucker for crooked, leaning buildings. Particularly the right one looks extremely unconvincing, and just plain stupid, but I like the tower-like part of it. They both lack a porch, that I was planning to add, and which would also add more variation depth wise (right now their elements just vary height wise). Also want to make them very integrated into the environment, so I'm gonna try having some large tree lean on them or something, to make the whole sagging thing a bit more believable as well.
Edit: Also, now that I look at them I notice a common flaw, in that when we lean stuff, we tend to lean them just to the sides, which is a boring and flat solution (it's the easiest though), so I'm gonna try having the different halves sag to opposite sides depth wise as well (i e, have one half lean away from us, and the other towards us).
080517:
Made two new design sketches. I tend to do one or two a day until I find one that feels like it has promise.

The right is an experimental sign design, and in the house one I tried a design with a walkway/stairway thing leading up to a door. Vertical variation like this tends to add interest (Bill Tiller (the Curse of Monkey Island Background guy) is a sucker for this). It's easy to go for the generic approach, with having everything on a flat groundplane, so it's often beneficial to at least test some vertical variation when you design stuff.
080519
Pretty close to the last one, less messy, though just barely:

The design is pretty inconsistent, particularly the left round tower thing, but the silhouette looks pretty interesting. One thing I'm going to try in the next one is some diagonals, depth wise (now it's an L shape, this would add some \ shapes).
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Part II080601
Haven't really had time to do any sketching until late tonight, which is unfortunate, since I really enjoy this step.
Here's what I hastily came up with:

I sketch in this zoomed out size (about 12% of the document size), where the actual size of the document is more than twice the intended end resolution. The nice thing with this approach is that I can then just keep on refining if the "thumbnail" turns out like I wanted, instead of having to resize it, and by doing so get ugly artifacts and blurry shapes. The high resolution keeps the strokes sharp, and allows me to enlarge areas without artifacts or blur.
I start out with just loosely n quickly scribbling down some ideas for areas, after which I paint the canvas almost black. I then "light" the scene, as oppose to "shade it", so instead of going from a white environment and adding shadows, I start with darkness and add light. I find that this helps me design the light much better, as I need to selectively and intentionally add light, since it's not there as default. It also keeps the image from having too bright values, which is easy if you go from a white canvas. (the reverse is true when going from dark though).
In this one I tried out some back light, which creates large shadows n thus low contrast areas, which should help keep the mood somber. I also tried having it create a desolate feeling by silhouetting the swing, which I put to the right, against the bright sky. The placement isn't optimal, and the general balance hasn't really been considered. Just trying out my first ideas. Gonna add a lot more vertical difference, as it's very flat at the moment.
080603:
Here's the latest sketch.
With outlines:

Without outlines, to get a better view of the general shapes:

Still just trying out ideas, and this one is lacking the nearby farm, but I managed to get the windmill in there in the center left, and I think I could fit the farm around that area as well. Or perhaps on the right side of the house.
The lack of real foreground is bothering me, but I think I'll just add some stuff on the right, that'll nicely overlap the currently empty yard as well, and get a few lines pointing towards the house.
080626:
(I think posting the current update in your bump post might make the thread more exciting, so here it is:)
Continued with the last sketch:

800xsomething

Added more foreground (don't ask me what that close thing to the right is - have no idea), which adds a few layers to give it more depth and lines, where the bottom part is leaning / to compensate for the heavy \ lean of the top (which the fence on the right also helps out with). The balance is still pretty messed up, and I'm once again
paying the price for sloppy pre-work by now having to try to fix things in this less flexible state.
There are many other issues, such as readability of the bridge (which is to the right beneath the sign post thingy, the stairway on the right side of the house, leading downwards, and other things.
Oh yea, I also flipped it horizontally, which is when I discovered the heavy \ lines of the upper part. Flipping it horizontally n vertically is a great way to spot these things, and also to see the image in a new light. In this case I ended up liking it more like this, but I might go back.
I've focused the light more on the right side of the house, to draw more attention to the center of the image, and kept the left in shadow, which also creates a nice silhouette against the sky. The bright sky is an annoying problem, as it creates strong contrast everywhere something silhouettes against it, which pulls focus. This could be countered by blocking it out with trees n stuff, but I want a pretty open feel, which that would rob. So I've limited the blocking trees to the sides to lower the contrast in those areas, and also frame the subject.
All in all, the melancholy feel is pretty much non existent at this point, much due to my weakness for strong sunlight, but I'm hoping it can be fixed with some details n colour).
I added a small character to help with the scaling, which is another issue, particularly with the fence and sign post.
080630:


This is the latest composition I've tried, and I think it's getting close to something I'm happy with. I've basically pulled the mid ground closer to the camera to become something of a new foreground, and ditched the old one. The bridge is now a wooden bridge, that is more easily read than the former stone one, and also produces less contrast which steals less focus from the house. In addition, it allowed me to quite easily add a stream beneath it, something that the other solutions (of which there have been
many didn't provide. And even better, the sign is now close enough to be actually readable.
Other benefits: The sign now frames a bigger portion of the far background (where the windmill can be seen (a very messy area atm)), the fence now goes around the yard, forming a nice big curve:

which a) leads the viewer around the bottom part of the image up towards the house and b) as it's slanting /, it compensates for the \ lean of the top part of the image.
The downside is that there's now a pretty large distance to the house from the bridge, which isn't ideal. Also, atm, there's a perspective issue at the bridge, where we're pretty high above the character height, which isn't ideal either. It can be fixed by lowering the camera, which I'm considering.
Some other things: I but the right side garden area in shadow to detract attention and pushed the swingset further back, to open up the yard and increase readability. The swingset has been a problem ever since I put it in.
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Finally got around to try some colours:

Larger resolutionNot very happy about it, but it's a start, and sort of capture a melancholy feel.
Must say I dragged my feet quite a bit about this, as I knew that the value sketch called for quite a transformation to fit the theme. Which is a shame since I really liked the look of the value sketch.
Having to open up one of the windows was annoying as well, as they create these weird gaping holes. My intention was to go with the right one, but the large centre one looked less bad, and does provide more space for the character.
Speaking of character, I tried quickly adding one, but the size poses a problem, so I had to go with 800x600 to make her fairly visible.

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080911:
The second colour attempt:

Think it looks better, but lacks the melancholy feel that is called for by the script. Come to think of it, I think it's the brighter values that I like better.
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080920:
Most likely final version, though there are still things to refine:

Some cleanup and colour treatment, and also added a couple of toys.
Edit: Fixed links