Bolton is a good choice in terms of experience and being able to hit the ground running. Especially since he has his network of informal channels from his time at the UN. Only downside to him I can see is he tends to go a bit policy wonk when pragmatism is needed, but that's only a tendency, not a habit.
And Flynn? For God's sake, NO! I said it elsewhere, he couldn't pick which shirt to wear if you offered him a choice of two white ones. Smart guy, good listener, good memory, but indecisive as hell.