I really hate the idea of Flair being GM for most of the reasons listed. Let him go to Ring of Honor, or TNA or wherever. His time is done and the impact he would have on those promotions would be marginal at best. So let him go, simple as that.
Now as far as who should the next Raw GM be? Well I would love for them to scrap the concept all together, but I doubt that will happen. It would probably be a heel since Smackdown has a face GM, so my personal choice would be Bishcoff. By far the best on camera GM they've had. I doubt that will happen based on the whole CCW thing, so who else?
JBL-A recent departure that many fans would still recognize. Great mic skills and I never could stand him in a good way. Meaning he got the heat necessary for this role.
Randy Orton-No chance in hell I know, but this would be an AWESOME swerve. Orton is out of the Fatal Four way due to the beatdown HHH gave him. Vince comes out and BLAMES HHH for the mess Orton caused. "You couldn't take him out, You couldn't protect my daughter," so on and so forth. "You caused my family hell now I'm going to give you your personal hell," and he names Orton GM. It would be temporary of course but it would turn Vince heel again, freshen up a fued that WWE seems to not to be able to let go, and would turn HHH back into "a man versus the power" which WWE fans love. Like I said no chance in hell but I would love to see it.
Matt Striker- Great mic skills, can generate the heat. He's being wasted as a commentator. They don't want him in the ring that's fine, but I think he'd make a great heel GM.
Anyway, those are my humble thoughts.