Should I join a pool? I've configured the large (8x) GPU image on AWS at 2.60/hour. I ran it goes few hours after setup and mined nothing.

This was my first foray into mining.

Given this setup, am I better placed to join a pool? And what pool should I join? (Some pools reward the biggest contributor and others payout shares.)
You are unlikely to collect rewards consistently (or at all) solo mining with that hashrate. You should join a pool to smooth out your expected return, unless you are okay with the posibility of earning nothing for long periods of time (or are a very lucky person).