The closest beach Marriott would be the Marriott Delray Beach, about 8 miles from Boca Raton. There are good restaurants on Atlantic Avenue, within walking distance. Otherwise, there's a Marriott and a Renaissance in Boca near the Town Center mall, north of I95 off of Glades Road. There are a lot of restaurants in that area, too.
We just went to the Marriot in Delray beach for a family reunion My husband and I have been their before alone and it is wonderfull. But when we took our 3 daughters and 6 grand children there was a problem eating together for dinner they were all booked and there was a celebration going on in the street so the res. were full. With some pushing they gave us an outside table for dinner the second night and it worked .