i've been looking in to getting one too. from what i've read, the most common problem people encounter with portable gas grills is that their size limits the heat they can emit. i think typically, the smaller the surface area, the lower the heat output. may want to do some googling to make sure you purchase something that can properly/thoroughly cook whatever you like to eat when you camp.
the weber go anywhere series is what i've been looking at. i like the 1520 in particular.