Tournaments can be fun, I host them occasionally for a change of scenery but make mine deepstack and structure them in such a way that everyone gets a good few hours of play. You can do that with rebuys as well. I don't want people making a trip, however short, to get knocked out early.
You don't mention what you play when you play cash but if it's only Holdem then a sure fire way to spice things up if the games are getting stale is to mix it up a bit. I host one group that moved from Holdem tournies to full-on Circus Cash in about 4 sessions. Start with Holdem and variants, the various Pineapples and Super Holdem etc, then add basic 4 card Omaha, then 5 cards, double boards etc, Hi/Lo, some Stud varieties and then on to the more exotic.