Gumbymom is making good points about housing. My son only applied to four schools and was notified that he was accepted to each at very different times (January through mid-March). However, he knew all of his options before housing opened up for any of the schools. We strongly encouraged him (okay, we MADE him) choose the week before Cal Poly housing opened so that he would be able to apply on the first day. Other schools had later dates, so Cal Poly drove the decision date. In our minds, deciding by May 1st would have been really late, even for a school that has a Freshman live-on requirement.
Conversely, his girlfriend pushed off her decision between Marymount Manhattan and Sf State until the last few days of April. By the time she decided, the decision was made for her–NEITHER school had on-campus housing available. She was leaning toward SFSU and that tipped the scale since we live closer and she could search for housing more easily. However, had she not found a place through a family friend, she would be at the local JC right now.
Cover all your bases. Good luck!