First thing you need to ask yourself is what are you building for?

Do you want to build a castle that you will only need to use a tiny corner of for actual game activities?
Do you just want to build something safe and functional?

Personally I lean toward being functional and safe and not over build.

Then you have to decide what type of house design you are used to?

Personally I enjoy houses on stilts type of look. So uneven terrain does not bother me. in fact I find it nice to look at. I prefer a varied terrain over a flat one. its just more interesting and dynamic. Probably has a lot to do with where you have lived though.

Although if you want to build enormous places for the look rather than function you might be better off modding or something. Can't even imagine harvesting all that stuff for some of the outrageous things I have seen some people build.