My fanny pack has seen me through two NYC trips (including the Greyhound ride up)and countless trail walks. It has a mesh backing and a VERY roomy main compartment with two integral Nalgene water bottles.  Its an Outdoor Products from WalMart.  Even has reflective trim!
http://reviews.walmart.com/1336/10928121...ews/reviews.htmGood luck choosing! 
Thanks, Finn. I haven't ruled out a fanny pack so I'll check this one out.