Keep the Legoland hotel! It looks like so much fun! If you stay there, you can literally walk to the park, so it's easy to run back to your room. It saves you the parking fee at the park, and gets you in an hour early (definitely a plus since no free FP for Legoland). Plus, breakfast is included, saving on the cost of food for the trip.
Additionally, there are a bunch of fun activities for hotel guests at night. The theme park closes fairly early, so if you stay at the hotel, you'll have a bunch of cool
Lego activities to stay busy at night.
Save your Marriott points - they can be used anywhere.