I kind of agree with Ahnehnois here. The goblin chief is strange in wanting it to be a "solo". Why are the hero's so over matched by the goblin that he needs solo status?
Dragon, Beholder, Ettin.. These are easily visible. The story should drive the creatures abilities.
I could agree to some possibly "elite" style templates to toss on a creature. Giving them a reactionary attack or something to give them a little boost in action economy. Or even a boost to all their defenses to help negate a few more player attacks.
Wizards could be more threatening based on individual spells than on being able to take multiple turns. -- Summonings, protections, area spells, reactionary escape spells, etc...
Note when I say spells I don't mean PC spells, because Monsters should be built for different reasons than PCs.
Basically the creature should be solo on its own merits because it fits, not because he was slapped with a fat template and the characters wouldn't have the least bit of understanding of.
-- I'm a big fan of 4e, and the minion/standard/elite/solo, flat math is handling the minions well enough. Solos though I think real thought should be put in before putting the label on a creature.
-- An elite template, solo creatures.. Beyond that GM's could probably customize to get the proper feel they want using those as examples.