I would second the eating insure advice. You said "one nicer meal" out, pick an offsite restaurant (& bonus for a slower night of the week, as sometimes you can find additional deals on Monday/Tuesday). Instead of eating at Downtown Disney, as you mentioned earlier, eat at a restaurant at The Crossings (Chevy's has large portions, chips/salsa unlimited, free soda refills) for much less they'll will pay at DTD. You could easily walk (once you cross the street) back to DTD for the experience, shopping, people watching, etc.
If your parents are renting the car, try to have them drop you off at the parks each day to save parking fees. It is usually closer and saves steps as well. The parking attendants will allow drop offs and direct you to the spot. You could always se Disney Transport from the parks to DTD and get picked up there, or one of the resorts if it were closer for the pickup person!