Hi ,
I think you should go for it, but be prepared not to get a bid ( as stated above.) Even if you don't get in a sorority it is cool to get to know new people, I say think of it as an adventure. Also if you do get a bid from a sorority even though they may not be your top choice accept it and see if it works for you. Coming in as a senior also has some benifits, you are more mature and therefore will most likely see the "true reasons to join"
I will warn joining a sorority as a senior has it's draw backs-- the new member programs are normally aimed at helping freshman women become aclamented to the new campus as well as the sorority, also you may feel left out because of the small amount of time you have to invest in the active chapter.
Personally I believe the positives far out weigh the negatives. So take a shot at it
