I also have to do a persuasive speech, but not for another week or two. My teacher is considering a ban on sports since I've used it on almost everything so far and so has half my class (BTW I got an A on the Fantasy Baseball Speech, and I got extra points because I had "extensive knoledge" of the topic).
My idea would be about the DH rule since you can find info on it and you can take a firm position. Just feel passionate about your position and be clear. Good luck!