we were basically at those ages last summer. We had a great time at the Carousel hotel in Ocean City. We got an oceanfront room with a big balcony. The balcony was big enough for all 4 of us to be out there comfortably. We ate meals on the balcony. We sat on the balcony while kids were napping/ after bed/ etc. We could walk out to the beach and play in the sand. It had a 'pirate ship' play structure that my almost 3 year old could play on forever. The kids liked watching the ice skating in the lobby. They also liked standing on the balcony and watching the kites flying/ parasailers/ etc. It does have a baby pool- but it is an old fashioned yucky one and we did not go in. The room had a little kitchenette with a fridge and microwave.

Rehoboth. Funland.
Lancaster/Strasburg. Train museums, farm tours, Cherry Crest Farms, and Dutch Wonderland.
At that age a resort hotel with condo suites and a zero-entry pool with nice landscaping is nice for mommy. Something with a view for the person stuck in the room with a napping baby.
I would insist on full kitchen and w/d with kids that age, and a separate bedroom so you can stay up and chill with DH. A vacation rental. I ain't camping with no 6 month old.