(Psi)SeveredHead
Adventurer
well, the last solo of the campaign (the PCs were level 24, I think?) and the solo was level 27. Not sure they were encounter powers or recharge ones, but the solo had a daily or two, plus another daily that recharged once bloodied, and then had an aura, a nifty minor action power usable every round and the regular at-will power. The problem with the aura was that even at a high level, the players usually had some sort of item or power that allowed them to neutralize it and the guy playing the archer ranger had an uncanny ability to roll really high and would bombard the bad guys from a distance. (His father playing a defender/fighter was the opposite, had an uncanny ability to miss when he only needed a 4 or 5 on the d20...)
But, if all your solo has for her last 500 or so hit points is the at-will standard, at-will minor and hopefully a recharge power every 3rd round or so, it gets boring fast.
Are you the DM?
Monsters pretty much never get dailies. Any daily powers that a monster has should be an item power. Also dailies don't recharge unless they're reliable. So I think you're talking about encounter powers.
Good solos get nastier when bloodied. They don't just recharge a power, they get an aura (or a nastier one), their attacks deal more damage, they get a new attack type, their powers attack more targets, etc. A nastier aura should bypass some resistance. In addition, auras can have effects beyond mere damage.
Well-designed solos get multiple action powers (standard and minor attacks), usually getting two or three attacks just with a standard action, plus triggered powers... plus a way to avoid too much action loss.
I also have to say a level 27 solo is not a good challenge for a level 24 party. Two level 24 solos would be more interesting. The last time I threw an at-level dual solo encounter at my PCs, it should have been a TPK. (Instead, the enemies captured all but one PC.)
What monster was this level 27 solo? I want to take a look at it.