When I was playing around with my d12 system I did it in 6s...You could have more branches.
At level 1, pick a group between warrior, skill, or magic.
At level 2, pick an archetype.
warrior -> swashbuckler, knight, or brute.
Skills-> sneak, charm, craft
Magic -> holy, nature, arcane.
At level 3, pick sub-class.
At level 4 you get a feat.
level 5, get a group increase
Level 6 an archetype increase
Level 7 a sub-class increase
Level 8 a feat.
And continue customization on the way up.
so at level 1 you picked a class and (back then we called them races) and a a heroic theme
At level 6 you picked a paragon path
At level 12 you picked a Legendary archtype
At level 18 you picked a epic destiny
At level 24 you picked an immortal package
and in theory at level 30 you just ended up the game...
I was trying for each class had 2 built in good choices for each, and then each subset "warrior, priest, mage ect" had 2 that anyone in that group could take and at least 2 any non caster could take and 2 any caster could take...
As awesome of a concept as it was I could not make it work