We are doing one day at Universal and two at Disney and we are switching hotels and staying onsite at each park. The perks at Universal are too hard to pass up, and we like being onsite at Disney for the closer access to parks and the transportation. Time is of the essence for short stays! As for the transfer day, thanks to online checkin at Disney, when we switch we can just leave the luggage in the car, do our Disney parks all day, then (if it all works correctly) go straight to our Disney room at the end of the day. One downside to staying at Universal the whole time is that you will be paying for a pricey hotel room and not using the perks on your Disney days. Plus you get earlier access to FP if you are onsite at Disney.