The problem with living crew is that-- as you mentioned-- they would evolve enough over time that they would lose interest in their original purpose. "Screw those embryonic proto-xenohumans, we xenohumans need to look out for 'Number One'."
Remember, the 'xeno-humans' would be as much our descendants as the embryos, just more removed. It's entirely possible to have far more massive populations in space than on the ground.
Hell, at some point intellectual curiosity would probably ensure the 'rebirth' of ground based humans. It'd just be after there's 10B or so space-humans in the system. As a bonus, that gives a goodly amount of time to conduct some terraforming on the target planet to improve it's suitability.
I know both groups would be evolutionary cousins. My point was:
1. A generational ship is much more expensive than a 'spore' ship containing frozen embryos.
2. If you're going to bother with a living crew, then you lose all the economy of the frozen embryos, and so why even bother with the embryos?
3. The living crew will diverge into a different, possibly-incompatible species over time, and thus their motivations may no longer be aligned with the original goal of the mission.
So: embryos w/ ship-mother, or living crew. But not both.
Finally: I assumed that we would choose our target planet well before launching, so no terraforming necessary. (But: wildlife & environmental hazards unknown.) The spore-ship would be analogous to tree pollen, floating on the wind; either it lands in a viable place, or it doesn't.)