If you are staying on-site you could do the parks in 2 to 3 days since you would have the unlimited express pass (not available yet on WWOHP ride or the new RRR roller coaster). If you are staying on-site you would park at the hotel be either self-parking or valet parking. The huge garages are where you would park if you are commuting from Disney to the parks. Once you exit the garage you would walk through City Walk to get to either park. City Walk is restarants, clubs, movie theaters, and shops. Universal offers a meal deal that is basically fast food all day. We have never used it since that is not the type of food we want to eat all day. We like Richter Burger for a quick meal and Finnegans for a sit down meal at Universal. In IOA we like Thunder Falls Terrace by Jurassic Park for a quick meal. We love Margaritaville in City Walk for a sit down dinner. If you are a member of
AAA you can get discounted tickets for the parks, a good discount on the on-site hotels, and if you show your card you will get a 10% discount at all the restaurants and shops (not Emerils). We go mid Aug every year and start our trip at Universal for two days (we stay at the Hard Rock)and then check into the Boardwalk at Disney. If you are not staying on-site my advice would be to arrive very early on the day you want to go to IOA since Harry Potter world can get extremely crowded.