I can approximate any aesthetic you need
e.g. for my mech designs I've been channelling FDs style from his MWO concepts, but with slightly less dangly bits...
buildings... no problem, just let me know what you're after and possibly some reference images and I'll give it a shot, or I could just let my imagination run wild and come up with something crazy.
2d elements should be reasonably straightforward, though I've never done any actual web or graphics design work. Working with vector shapes and all shouldn't be too much of a stretch from freehand painting.