I might not be the right person to give you advice, but I will anyway. Here is my perspective from an ET who got out in '95, having spent almost ten years in...
Prototype staff is good experience. I wouldn't have thought so before having done it, but it turned out to be for several reasons -- for one thing, as enlisted, it gave me a chance to qualify EOOW, which I wouldn't have been able to do otherwise. But I don't recommend staff pickup. It's backwards -- you don't want to spend your first two or three years as a staff pickup and then go to a sea command for the first time as a nubly first class. While a staff pickup, you'll get no respect from the sea-returnee staff, and you'll be limited in what you can do. What works out great is this; get your sea time over with FIRST, then do prototype duty just before you get out. It let's you prepare better, also, for getting out.
Precommisioning a carrier might be a good experience, but I would recommend going to a regular sea-going ship or sub, get it over with, then do what you want. Sea time isn't all that bad if you're single. As a Navy nuke, there's no substitute.
Good luck.