One thing I have noticed that can be quite helpful is giving a mini-Boss monster the Mythic Agile ability, as noted under the Spoiler:
Creatures with the agile template are quick and deadly, moving faster than their normal counterparts and striking with incredible speed and agility. An agile creature's quick and rebuild rules are the same.
Rebuild Rules: Init +20 bonus; AC +2 dodge bonus; hp mythic bonus hit points; Defensive Abilities evasion (as the rogue class feature); Speed +30 feet for all movement types (up to double the creature's base movement speed); Special Attacks dual initiative.
Just the dual initiative alone helps turn these into a viable threat without a large number of minions to help. The +20 initiative bonus also helps ensure they will go first under most circumstances.
Oh, that IS nice. I'm going to add that template to Mokmurian for tonight's campaign. I've given monsters Mirror Dodge to buff them up, too. It's amazing what Displacement giving them a 50/50 chance to miss with him having the option to teleport away if they hit can do.
The Mythic Chimera Soltengrebbe from Sword of Valor was built around dual initiative, and he was a magnificent challenge for the group.
This looks like a job for E6!That's a choice.
Except you don't have any of your cool stuff by level 6 now, do you?
Maybe e10 or 12 ;)
You have plenty of cool things in E6 it's just that they come from feats and being able to invest in long feat trees and a variety of feats.