I just bought a Thinkpad X140E. Its screen is only 1366x768, but I think its other features might readily make up for that. For one, it's got 8 hours of battery life. The day I configured it (last Friday), I started ~9:00a, downloading and installing applications, and removing others. The whole time I was also streaming Uncle Sam's Misguided Children Internet radio (using RealPlayer Cloud). I stopped listening and shut down around 3:00p, and the battery meter was still showing I had another two hours.
It is also very durable, which might be good in your environment, and with the screen only being 11.6", it is small and light. I've not done a lot of gaming on it, but I loaded the original Guild Wars on it, and in my brief test in unpopulated areas I could max everything (I suspect the CPU will hold it back some in a crowd). I suspect gaming battery life will be considerably shorter, but I'd expect at least 4-5 hours.
At $540, it may be a little more than what you want to spend (and I also added another 4GB of RAM; you won't have to do that), but it looks like a good choice.