I've been spending summers on the Cape for years! If you're looking for a nice, family friendly hotel, try the Bayside Resort. They're online, located in the Yarmouth area. The rooms are clean, some even have in-room whirlpool tubs! There is an amazing breakfast spread every morning: coffee, teas, hot choco, juices, waffles, cereal, bagels, fresh fruit, yogurt, pastry, and more! You can eat in the breakfast area or bring back to your room. They have an indoor and outdoor pool, hotel lounge for cocktails (enjoy or bring to your room!) and more.
Its a very central location and I've never been any less than thrilled with my visits here!!