I stayed in the Fairfield Inn in May which was right next to Millie's on Harbor Blvd. I actually really liked Millie's. It wasn't that expensive and you got a real decent amount of food for the price. It was a good option for when we had left the park and hadn't eaten anything other than Churro's or pretzels. It was also more satisfying that swinging through the McDonald's.
Next time I visit I am planning on staying in the same hotel and going back to Millie's.
Added bonus: Millie's delivers room service to Carousel Inn, Anaheim Camelot Inn and Suites and Fairfield Inn.