I agree that cash prizes should be eliminated from Hackathons.

I'm not sure about Team Selection, whether to have random, pre-determined, or 'quick pitch' style.

Sometimes Hackathons can be a great experience for the participants. Sometimes, however, the evaluation criteria can ruin. We had one of the only functioning projects, but were docked points for using Twilio instead of AT&T's shitty API. (One of the Sensei's even told us to use Twilio.)