Thanks for the help guys. I'm reluctantly starting to conclude that I can buy a charger than is either lighter or faster, but not both.
There are a lot of fast claims on chargers, but even a 4 hour charger isn't that fast if the quoted time is for two 700 mAh AAA's and I need to charge 4 x 2500 mAh AA's. A lot of fast chargers will actually take about 6-8 hours, which is too long to be pragmatic. Thus all 2 x AA chargers seem to be out, and only the faster 4 x AA chargers remain.
At present, the Duracell CEF27 (1st generation with curves) seems like the best shot, as I can charge four high capacity AA's in 3 hours (2hrs is for 1700 mAh), which about the same time as what our iPad Mini will take. Unfortunately at 108g it is hardly lighter than the slow charger I have now (115g) and it also appears to block both receptacles on a wall. However anything lighter is substantially slower. The Watson 79g "4 hour charger" sounds promising, but it's rated at 280 min for 4 x AA, which is almost 5 hours and that's likely for 1800-2000 mAh batteries, so my 2500 mAh ones would likely take nearly 6 hours.
Noteable mentions are the Sanyo XX Charger (220 min for 4 AA, 111g), the Panasonic BQ-390 (8-10 hours, but 85g) and Sanyo's 2 x AA Compact USB charger (55g, but much too slow for charging 4). The new generation of Duracell CEF27 is also interesting, as Amazon says its 82g, but it appears to be slower than Gen 1 with a claim of 2.5 hrs for two high capacity AA's.
Brian, this is actually just for my wife and I's headlamps. My camera uses unique Li-Ion batteries, but I have 3 of them so I should be fine there. Opting for NiMH over alkaline or lithium also saves quite a bit of money over the trip, and it avoids being reliant on finding batteries in stores. While not likely a real problem, it's nice to be as in control as possible. Considering I need to charge my camera and iPad Mini anyways, 2-3 hours for charging doesn't really change anything.