I remember in DCUO, in one of the earlier raids, the group had to split into two groups, that each went down a corridor. Each group had to defeat a mini boss for the other groups door to open.

Also, Paradox Wave, while it had it's issues, had a good set up. The main boss was in the first chamber, which had four tunnels coming off of it. Each tunnel contained some trash and a hard mini boss, each with its own loot. If you decided so, you could leave one to all four of the mini bosses alive, and just attack the main boss. But at the end of each phase, on of the mini-bosses would leave their tunnel, and you would kill while contending qith the main boss as well. If you couldn't down it fast enough, the next phase would start, and you would have two mini bosses.

Also if you left them up, they dropped a better tier of loot than if you killed them in their tunnels.