So, in this vein. A brief blurb about good racial choices for classes.
With the floating +2, humans can manage to excel at any class. It goes in the primary stat. You may not want to be something like a Star pact warlock, however, unless you ignore your at-will power, only use eldritch blast, and take con only powers.
Cleric-
Dragonborn (str based beater)
Dwarf (wis based blaster
Elf. (though the dex bonus isn't particularly useful for the class, it does help your init and reflex score)
Human. (blast or beat)
Fighter-
Dragonborn and human. All others need not apply.
Yes, you can do a dwarf or elf and buy an 18 str the hard way. you still won't be as good at attacking as a human or dragonborn
Paladin
Dragonborn and human again.
dwarf is present again, but lagging. half-elf could consider the idea, but really, this guy wants to be a warlock.
Ranger
elf wins ranged. Halfling wouldn't be terrible, except he's stuck with shortbows or thrown weapons, and the charisma doesn't do a thing for him.
dragonborn has a place as a melee ranger, though again the charisma is iffy.
Eladrin are passable ranged strikers. The int bonus goes to waste, however. Maybe put your 8 in int if having a penalty bothers you.
human can do either role.
Rogue
halfling! No, really, this is your thing. Who needs favored classes.
human, of course.
elf isn't doing much with the wis bonus, but the dex and your innate speed and rough terrain shifting makes you amazing as a rogue. Similarly, the eladrin isn't doing much with his int bonus. Someone might want a teleporting rogue, but honestly they shift so much, the elf is by far the superior pointy ear.
Warlock
Depends on the build, but this class has room for many, many races, mostly because half the races hand out charisma bonuses. Expect to see a lot of fey warlocks.
Con- human, dwarf, half-elf. Extra bonus here is you can pretty much ditch charisma if you want to, and shove everything into Con and the leftover into Int. Go with 20 con, 14 int, and jack them up at every stat increase. Put the leftover pity point in charisma. You'll get a +1 out of it at level 11.
Cha warlock- tiefling, halfling, dragonborn, half-elf, human
Really, this class is made for half-elves, with one caveat. You aren't going to get a particularly useful at will power from another class until we see more classes. Someone else needs to be primary in Con and (especially) charisma, since so many of the bloody races have charisma bonuses.
ironically, as has been mentioned before, tieflings are comparably lousy at living up to their infernal heritage. Star doesn't look that great for them either.
Warlord
Hey, guess what? Humans and dragonborn, again. We may need another +str race... just, you know, as a thought.
Tieflings can hit the 18 the hard way and jack up the other two stats, but apparently all the attacks are str based, so this doesn't matter that much. Half-elves can do something here, too, I guess, if we really want to continue with second tier choices.
Wizard
Human, tieflings and eladrin. Glad eladrin actually have a niche. Having bonuses to paired stats isn't that helpful. Luckily wizards don't have to care much about their secondary stats unless they want to.
So, yeah. The lesson here? Playing against type doesn't pay that well.
So for the KotS characters, race-wise:
change the fighter's race to human or dragonborn
the paladin is fine
the wizard is fine
the rogue is fine (actually, racially, he's ideal)
the cleric... would be fine if he were a warlock. As it is, he's boosting a secondary and tertiary stat, Yeah. Don't do that. Pick a combat style and switch to either human or dragonborn, or dwarf or elf.
And yes, I know, some people will have problems with this. This is about optimizing them though. You want a +2 in the stat you actually attack with, not your secondaries. And generally speaking, 18 costs a lot, the hard way, but when all is said and done, you don't want to have less than an 18 in your attack stat. Buy a 16, add +2 from race, and you've got a fair amount of points to spend elsewhere, but going less than 18 in your primary stat is a bad plan- unless you plan on solely being a healbot, you're going to fail at your actual role.