Are the Dark Sun races really so imposing that you can't make balanced first-level versions?
Half Giant:
+4 str, +4 con, -2 int, -2 cha
+2 athletics, +2 intimidate
Large Sized
Can retrain twice as much as other characters
Thri-Kreen:
+2 dex, +2 wis
+2 acrobatics, +2 nature
Natural Armor
Trance
Claw Fury (see below)
Claw Flurry (Thri Kreen Racial Power)
Encounter
Standard Action, Melee
Effect: make up to four unarmed basic melee attacks.
Sure, eventually the Kreen could do a lot more stuff, but he only got that at later levels--perfect for modeling with racial feats.