I've been doing P90x and it's been working wonderfully.

Plus, I've also been running 5ks every other day and 10k on the weekend. As much as you hate it, it's great cardio. If you really want to change it up though, I suggest swimming, bicycling, or doing some sort of martial arts (kickboxing, taekwondo, kungfu, etc).

Pull ups vs chinups? I prefer pull-ups. It builds the lats which are essential for fencing (not that you'll be doing fencing). And, it just looks a lot cooler.