Good question, and I'm not exactly sure how to answer it.
Crossfit workouts are designed to be ingeniously simple, yet brutal. Like, for instance, one that I do is called the "Chelsea" - it involves doing 5 pull ups, 10 push ups, and 15 squats in succession each minute on the minute. So, basically, you do 30 rounds of that - 5 pull ups, 10 push ups, and 15 squats - for 30 minutes. The first 5 rounds or so you'll be like, "Hey, this is whack - I fucking own this shit." By round 15, you will want to punch yourself in the dick for being so stupid to try this.
There are a bunch of crossfit routines - just do a Google search for "crossfit routines" for examples. The nice thing about them is that you can lower or raise the intensity of them at will by doing fairly simple things, like adding weigh or trying to complete the routine in less time. This would work well for you: you could go slow/easy/less weight to begin and kind of work your way up.
The stuff you see on Insanity and P90X is basically crossfit stuff. It's all about doing full-body stuff in a shorter period of time for an intense workout. Another nice thing about the crossfit stuff is that you don't have to be in the gym for 90 minutes. Rather, you can complete a great workout in 20 minutes, even less.
Does it kick your ass? Yes. But I've found - for me - that unless I'm drenched in sweat and feel like I want to puke/die/quit, then I'm not doing it right.
I'm a huge proponent of trying different things to see what works for you. I've done a fair amount of fitness stuff and workout things, and crossfit has been great. My body looks better than it ever has. Try it and see if it works for you. If not, oh well - there's plenty of other stuff you can try next.