Some great work there Bob. I agree with Dune on the water, getting an almost mirror look will really amplify this I think.
I was playing around with Walli's dry grass pack the other day, and I've made a variation tile'able texture that might work really well here. It's at work atm, but I'll happily upload a TGC for you to have a play with. What's quite good about it, is that the built in TG grass population does most of the work, and then you use Walli's models to break that up a little further. I like your customization on his texture to make them a more 'dry tan' colour.
Your autumn trees I wouldn't touch. They look great. And the landscape is interesting enough to not have too much happening on it (although that maybe ecologically a little wrong, who knows and cares, it's your scene).
I maybe tempted to put some dirty reflectiveness on those windows though, which is little challenge in it's self. And the chimney texture might need something to break up that 'screen mapping' look, maybe another stone map.