I'm 5'10, 150lbs, with a pretty small upper body. For dress pants, Gap has some nicely cut pants that don't look like parachute pants.

For Jeans, I go with Levis 527's, and recently AE's Slim low rise boot cut jeans. The problem is I am a 30 waist, 30-32 leg depending on brands, were a 31 would fit me the best, but no one sells 31" legs

For t-shirts, I have to go with XS from both gap and AE. Target's house stylish brand (Mu-somthing) smalls used to fit me great, but last year, there S magicly got bigger, and now they look pretty baggy (in most case)

For dressshirts, Gap has Premium fit shirts that are a more taylored/thinner cut shirts that fit me nicely in size small. At AE, I can get away with wearing their XS dress shirts. I don't know if they still have it, but last year at Steve and Barries, I bought a few dress shirts that are made of a stretchy material (I think they are 2% spandex) that are cut great, and they were sub $10. I've actually had alot of compliments on those shirts. However last time I went in, I couldn't find any more cut like that.