I use the 2 1/2 gallon bags (you can get them at Walmart, Target etc.)
. Sometimes I just use one for my socks/undies, one for DH's sock/undies, etc. to make it easier with packing and unpacking and not having to rummage for the small pieces of clothing. Sometimes I also do an entire co-ordinated outfit (shirt,shorts, socks, undies, hair ties, etc.) in one bag for easy grabbing, especially if I have something I particularly want for a specific park or restaurant. It makes it easier for everyone (and by everyone I mean ME!
since everyone's clothes are apparently my job
)Less time spent looking and deciding, just grab it and get ready since we're always on the run.
I've also seen commercials for the 2X & 3X sized bags, but I have yet to see then in any store near me.