I use a red American Tourister duffel bag that's part of the luggage set my mom gave me for my birthday last year. I usually go in the morning, shower and get ready for work there, and the duffel fits the tons of stuff I bring with me.
A JanSport duffle/carry-on bag in a pumpkin orange color. It's the best gym bag I have ever owned. It has tons of pockets throughout, and even has a special plastic pocket inside for wet swimsuits. I got it from ebags.com.
A plain light blue slouchy back-pack type bag that I just throw over my shoulder. I don't care what happens to it, and it holds my water bottle, Keys, and ID. haha, wow I think it's from the gap. It's weird, because I'm one of those girls who wears make-up to the gym, but I care more about getting an awesome workout ( and being able to throw my bag on the floor) than looking super fashionable. I think I'm going to pick up a sports one in a similar style ( like a pink puma!) just because I'm getting sick of this one. I work out like 4-6 times a week ( more like 4 lately) so it gets good use!
I haven't been to the gym in forever since I got mono and felt crappy all the time, but I'm really starting to feel better and am determined to resume my workout schedule.
my bag was a cheapo recycled tote, but now that I bought that yellow Target Luella bag, I think I just found a good use for it (it's too big for an everyday normal bag for me).