THANK YOU all for the great feedback! I guess I should've trusted my instincts; I was thinking the small was better, but seem to be having serious sizing issues this season.
Details on the jeans: They're relaxed straight leg jeans from the GAP, 100% cotton and no stretch (my wash isn't available any more, though), "1969 original fit selvage jeans", link to similar:
http://www.gap.com/browse/prod.....=311929002
Details on the tank: It's from JCrew Factory and comes in 4 colors, link: http://factory.jcrew.com/women...../50549.jsp
Also in stripe: http://factory.jcrew.com/women...../36502.jsp
Angie, thanks! I love tanks, and I know I have a good shape for them... unfortunately we have very little hot weather to wear them *sniffle* Like you I have to be very stern with myself and not buy more than I can realistically wear at the start of the season!
BJ, I do think a pear would work these jeans! I have a proportionally ample seat heh, and sized up in these to get a really relaxed fit (they're already relaxed to begin with). Info about the jeans up above!
Annaj, no worries the smaller size is loose enough to semi-tuck