One idea I had was having a few classes that specialize in particular ways of hiding from/getting away from/destroying enemies. Possibilities:
Cipher: Specializes in technology. Can access areas/chests locked behind terminals. Can deploy bots. Can disable droid enemy types. etc.
Scavenger: Specializes in finding things and stealth. Gets a bonus to find certain things. Can utilize stealth abilities to avoid being seen. Can find hidden entrances.
Commando: Specializes in firepower and armor. Gets damage and health bonuses. Can deploy stationary turrets.
Mystic: Specializes in something similar to 'the force'. Can cast spells that do various useful things - maybe teleport, maybe fire missiles of some sort, etc.
One idea I had was having a few classes that specialize in particular ways of hiding from/getting away from/destroying enemies. Possibilities: