Structure for a 2 hour tourney?

[Galilee]

I've got the awesome responsibility of structuring a tournament for a group of 6-8 players. We want it to last a few hours, so it's a bit like a sit'n'go and we can play a few in an evening, but even so I was thinking of allowing rebuys in the first hour so no one ends up sitting out after busting in the first hand.

Does anyone play this kind of tourney? Does it work? Or should I stick to a longer, more drawn-out game? Any advice on blinds structure and other details would be appreciated.