We went two summers ago. We stayed at the John Carver Inn. The pool was great. My kids loved it. The hotel was pretty nice. The staff was really helpful with ideas on what to do. The restaurant in the hotel sucked! We were able to get discounted tickets for both attractions here, and it was a good deal. We found out that they also do haunted walking tours at night in Plymouth, but we just didn't have the time.
The first day, we walked down towards the water front and poked into historic buildings. We did the Mayflower II, the rock (what a joke!), and then walked along the road by the water, looked in shops, got ice cream, etc. We walked back through a very pretty park, walked past the grist mill, and then back to the hotel for dinner and swimming.
The next day, we did Plimouth Plantation, which was really fascinating. You can go as fast or as slow as you want. My kids enjoyed interacting with the Pilgrims. We drove back home later that afternoon.
It was a really nice trip. Enjoy!