I definitely want to focus on CQB missions. It's such a challenging and dynamic environment that is hard to simply shoot your way through. Also wouldn't mind missions with a lot more civilians.
As for hostage rescue, the mission shouldn't end if a single hostage dies. But a counter of hostage deaths at the end would be pretty cool. There's definitely a lot of cool maps to use. Any you're thinking about in particular other than the embassy?
I imagine it'd have to be CQB heavy to make it challenging, especially if the amount of tangos is going to be lower than usual.
There's a couple of custom maps that might be perfect for this sort of scenario.