I tried P90x while out of town (my family had it unopened and wanted to check it out). And I wasn't crazy about it. I liked the Yoga but I felt like there wasn't enough of a variety of body parts/stretches. In my opinion the workouts are way too long. I know it works, but I can't imagine it has great long term effects, especially for anyone that is not on the P90x diet (which is a little ridiculous). After 45min/1hr of intense physical exercise, your body begins producing Cortisol in response to the stress which can eventually hinder progression.
Personally, I think nothing beats eating right, lifting and cardio, and an active lifestyle. I love lifting but outside of the gym I always try to go swim, hike, play pickup games with friends, ride my bike at the skatepark, whatever, just have fun while being active.
As stated, I LOVE lifting. I have since I was 14, and definitely fell in love when I played football. I keep my workout well rounded, but my favorite body part to workout is shoulders/traps, followed by chest and upper back.
I don't know what its called, I think it's a pull, but you take a barbell, stand with your feet shoulder width apart with a close overhand grip, then you pull the barbell up to your chest until your elbows, forearms and hands are parallel with the bar, then lower it. Think of it as a close grip Lat Pulldown, but your standing and the bar is from the bottom, not the top. I use the pyramid technique and this one gave me some explosive growth and helps give some definition to the upper back. Then I love combining it by some doing dumbbell shrugs (with a heavy weight) dumbbell chest flys (slight incline) and inverted bench after (with give or take a few lighter/lower impact chest and shoulder exercises). Feels soooo good, and when paired with the right nutrition the results are great.