Over the years I've gradually built up about four dozen AA rechargeables... lots of them Energizers and other common brands. They work fine... When using flash, I'm often using battery packs that take an additional 8 batteries, for a total of 12 batteries per flash.
The chargers I use are inexpensive and slow. There are faster, but I don't know if the batteries charge as well as they do on the slow ones. The key thing is to start charging a couple days in advance, or if you use flash a lot rotate the ones you use and keep recharging. Toward that end, I've got two chargers that can handle 8 batteries at a time, plus a couple more that can charge 4 at a time. So it might take 6 or 8 hours to charge a set, but I can charge up all my batteries in two sessions.
I also think the flashes recycle faster with the rechargeables and that I get at least as many shots per charge as a set of alkalines would give me. I haven't run any actual comparison tests though.
I do carry a few packs of alkalines most of the time, too, just in case.