2/c cruises range from just over a week to over six weeks depending on where you go and what you do. I was on a submarine underway for 11 days, but I know some people went on boomers for five or six weeks. I don't know for sure, but I would bet the Surface 2/c cruises have the same spread.
The quality of 2/c cruises vary quite a bit. Some you can go to the Med, or Ireland, or somewhere in the Pacific. Me, I got to go from Groton, CT back to Groton, CT. It just depends on the "hook-up" that you get.
Experiences at CORTRAMID, on the other hand, do not vary as much. You will do one week of training with the Marines, SWO's, nukes, and aviation. In the aviation week you may get a T-34 flight, and flying is something you won't do in a 2/c cruise (unless they fly you to your ship). If you know you want to go aviation (guessing that because you're on AW), then maybe you can use the 2/c cruise to experience something you haven't done before and probably won't do again (being on a submarine for example). Otherwise, if you're still unsure which community to go into, then CORTRAMID will give you a decent picture of each community.
In my opinion, Aviation does the worst job of selling itself at CORTRAMID, but I guess if they have to sell you on being a Naval aviator, it's just probably not for you.