Most of the hotels in the area for the summer months do have a 2 day min stay. I didn't do hotel blocks, but rather gave everyone a list of hotels in the area and let them pick based on prices, etc - that may be worth a shot as well.
The Hotel Macomber is a nice, cute place right on Beach Ave that will do blocks and the rooms are moderately priced. 2 night min. Also, the Summer Station Condotel around the corner from the Alcott blocks rooms although they required a min 3 night stay. That was a good place for some family and college friends to say because they have suites with separate bedrooms ideal for sharing with multiple couples or families with kids.
Thanks for suggesting the summer station condotel, I called and for that weekend it is only 2 night required stay but no discount prices. Did you have any suggestions or comments from your wedding at the alcott.