On the 737s, make sure you avoid the middle (B and D) seats in Y. They're narrower than the window and aisle seats. Also, on the -700, one of the rows near the front of Y (forget which one in particular, maybe 7) doesn't have a window.
[Edited 2010-07-04 16:53:31]
Tho' I've belted you an' flayed you, By the livin' Gawd that made you, You're a better man than I am, Gunga Din!