I did Iyengar yoga before Ashtanga, and truth be told, Ashtanga is more dynamic. I found it less boring. It's also easier to follow and remember once you learn the sequence of moves. A lot of the postures are the same between different schools of yoga, so just like the martial arts, it is mostly just a matter of finding something that fits with your body and personality.
I cut back on my yoga practice after taking up kobudo, but recently have gotten back into doing it at least three times a week. I found it really helps with lingering tightness, especially in the legs and back. I avoid the bent-and-twisted leg postures because they hurt my bad knee.
Even just "sun salutations" are great full-body stretches. Wish i could find a good youtube, but i had problems with all of them! Okay, this guy's form is the best but he talks too much:http://youtube.com/watch?v=9P5PSqmnu88
You can do a surprising amount of damage to yourself doing any kind of yoga, so please find a reputable teacher who can adapt the practice to any pre-existing conditions you may have!