Hrm, at this point in the game a lot of the good places might already be booked up. When I went to Ocean City, MD last year we booked 9 months in advance. Having said that I would check out Ocean City (either MD or NJ) I've been to both and they are both fairly family friendly, NJ moreso. I know of some nice places in FL, but they are more than what you are looking to spend.
