I would steer clear of a scavenger hunt. For one of my buddies' bachelor parties the guy planning the thing decided to do a scavenger hunt and it was a fucking disaster. The planner tried to force us to take part in a bunch of shit we didn't want to do and it backfired. We ended up hijacking the thing, taking the bachelor to a slightly dirty joint, and buying him an evening worth of two-girl shows (thank you Montreal). That made him very happy and that is all that mattered.
The recipe for a successful bachelor party typically is booze, strippers, ball busting, enough places for people to crash, no set agenda, everyone focusing on making sure the bachelor is having a good time, and not talking about any of it when you get home. That is unless the bachelor is LDS, Jehovah's Witness, or a complete wonk.