I'd be a little taller, shorter face, shorter nose, super-straight teeth (my teeth are actually pretty good now...I'm just really anal when it comes to...oral? o.o), remove whatever gene it is that makes men grow an abundance of hair around their arse, and I'd also like to put in some unique little 'mark' that any later members of my family would have - like a streak of different-coloured hair, or a unique birthmark. Weirdly, a straighter penis...I don't understand this curve business, no matter how slight.
Fixing my family's short-sightedness, likelihood of developing cancer, and chances of having issues with their thyroid would also be nice, if we're not going purely for the cosmetic.