I went to the Neiman's outlet and bought a Foley & Corinna bag (sort of like this one
http://www.google.com/shopping/product/13174991507349481782?q=foley%20&%20corinna=&sa=X&ei=SLyTUcraApTu9ATYmoGIBQ&ved=0CM8BEL8TMBI) that I now use as a diaper bag, essentially.
But I did this when #2 was 1.5 and #1 was 4.5 so I didn't need to carry nearly as much crap as I did previously. Now, I will usually have a couple of diapers in there, small pack of wipes, 1 set of clothes, and that's it. Works well for me but it wouldn't have in the days of bottles.