More than just Master traits or 1 + 1 advanced, how about some interesting combinations.
For example, one I've been toying with is "Doomguy Generalist." i.e., you do everything the Doomguy could do in the originals.
So:
Badass (supercharge doesn't go away as in Doom)
Dodgemaster (your sidesteps basically always work)
Shottyman (move and reload)
Hellrunner (you're the fastest darn thing in the game once again)
perhaps Ironman (HP to 100)
plus the necessary basic traits.