My old place was an apartment so I never wanted to put much up I did have a good bit of pictures in the livingroom/dinning room.
As far as this house goes, new wood floors, new carpets, new sinks, toilets, all new kitchen stuff, knocked out a wall, had to use drywall mud on EVERY single wall, fixed a few ceiling spots where nails were popping out, redid the bathtubs and new calking, all new hardware for every door/window new water heater, new water lines, new driveway... I think Im in the 35K-40K range on upgrades in less then 6 months of living here.
walls still need a few touch ups before stuff goes up, as far as the color goes we left everything basic colors so when time comes to sell, we wont have any issues. its a white with a slight touch of gray but mostly white.
Next house will hopefully be a 10-20-30 year home, at that point I wont hold back on anything I want to do.