I use a headlight when I'm camping - I used to have a princeton tech matriz with the 3 leds, but just upgraded to the black diamond Icon. Both use AA's (2 in the matrix, 3 in the Icon). I use NiMH's in them. If I'm going for 3 days or less, I put a set of fresh-charged batteries in, and take a spare set. If its a longer trip, I take the 12v car charger too. I have a 6 year-old, so backpacking ain't happening anytime soon, but if I was, I'd get a brunton solar panel to recharge the AAs. As it is, I can charge batteries for me and my wife no problem.
I've carried flashlights (usu a MiniMag, but other stuff too), and I've found that sitting and trying to read with a flashlight sucks. So does trying to cook breakfast if the sun hasn't come up yet. There is always something you need to do with both hands.