so far my experience with the foam roller has been intense. each time i've focused on one muscle group that seems like it needs a good deal of work, i stay sore for like 4 days. this started with my glutes. i've already noticed that my glutes don't get nearly as sore as they normally do after a day full of squatting, and they feel fine after rolling now. i've been exploring other areas in a similar manner. generally i'll go over most the body moderately, and then give focus to one area that has seemed problematic.
one thing that has helped me is dropping to my knees and putting a lacrosse ball beneath a knee (you'll have to put your hands on the floor like cat's pose to balance). i'll roll it all around the kneed cap (mainly below but all around). sometimes when i go to ju jitsu and it's cold and my legs are a little tight, plopping down into somebody's closed guard puts a noticeable tension on the knee, ankle flexor, and ankle. rolling out the kneecap for a few minutes really opens that area up.