Two of our favorite places to go are Virginia Beach and the Outer Banks. Both are wonderful.
In Virginia Beach it seems to be mostly hotels/condos on the oceanfront so you could get several rooms. We have not explored large houses there so I'll let someone else answer to that.
It is a city too. It is actually the fastest growing city in Va. so there's a lot of things to do for all ages, all tastes...shopping, restaurants, museums, galleries, as well as Beachstreet USA for several blocks one block off the beach and concerts on the boardwalk and regular events on the beach - at least at the lower end.
Even when deciding whether or not to have a reunion in the Outer Banks one question we also considered was whether we wanted a 'family' feeling achieved in a private home with one kitchen, a living room for all to gather instead of a lobby, a dining room for all to eat in and enough bedrooms for all. The Outer Banks is known for this. We especially like Corolla too because it has lots to do and lots of nature and yet allows plenty of time to relate as a family...those houses can have something like 30 people...I think I saw one that accommodates 36. And that's not laying all over the floor...that's in bedrooms with as many matching bathrooms, especially in the newer ones. In the Outer Banks we used resortquest.com and villagerealtyobx.com and had good results. Look them up.
But we do love both places. This is just an overview so you can see just how you yourself want to feel on your trip. Maybe a house is too much togetherness and hotel rooms would take care of that. Personal taste.