Does anyone have any suggestions for class + race combinations that are good fun and powerful?
You'll want a flexible party that can cover most skill checks. First one that comes to mind is Rogue - or Bishop with Trickery Domain - lots of checks that require a rogue. Some of which can make certain fights easier. Other checks can help you either get a surprise round or prevent an enemy from acting on first round. Other thing is that Rogue isn't that bad of a martial. It gets access to Mirror Image, Blur, Displacement, and Stoneskin; which are absolutely fantastic. It also can use wizard scrolls.
Another class is Bard. The songs it provides for party are very nice. Love the buff that increases DC of spells. It, too, also, has checks exclusive to Bard. Just as how Rogue can be used to make fights easier, get surprise rounds. So too can Bard. Speaking of which. Here's an encounter that favors it. Somewhere in Main Campaign you'll be caught in a Death Snare (these are challenge rooms you need to beat if you want to get out); where a Mastermind Flayer will call forth a Devil Lord. Only the bard can delay it or give it negative levels to make the fight manageable.
Besides those two. Rest comes down to what the party needs. For starters you're going to need spellcasters. How many depends. My recommendations will be: Warlock, Sorcerer, Wizard. I like Warlock because it gets access to a devastating spell called tornado blast. It does so much damage - can one tap some enemies. It also gets access to another spell that allows it to raise DC of spells. Which is desired if you want to win the fireworks war in end game content. Next is Sorcerer. Unlike Warlock, Sorcerer gets access to both Wizard and Cleric spellbooks. All at full progression. This is important because it means you have a contingency in the event Bishop or Cleric falls during battle. Wizard, unlike the aforementioned classes, has access to unique feats and a familiar. Familiar is nice because of the bonuses you can get from it. May not seem much, but the familiar bonuses do help.
So, after all is said and done, what would MY ideal party look like with the above put into consideration: Mage Knight (Blur, Displacement, Mirror Mage, Plus it can use wizard scrolls), Rogue, Bard, Sorcerer, Cleric, Wizard. Additionally I like to have my Wizard as an enchantment specialist because of Sleep, Chaos, and Confusion. Those spells help a lot in early to mid game content; but are useless in end game, lol, since everyone and their mother has innate Mind Blank which makes them immune to enchantments.
Besides that. I don't really have much else to say. Oh yeah! You get two important companions. Pizzara the Warlock and a Kobold Sorcerer. Hang on to those. They are going to be essential in end game content; where encounters devolve into Fireworks: Wizards edition.