If you book a package they only require the deposit. You can then pay it off as you go. Make money payments, weekly payments, whatever. You just need to be paid off by a certain date before your trip. So your scenario of paying off the hotel at check in won't work if you do add the dining package as it needs to be paid off prior to arrival. If you add tickets or dining after the fact, I believe that technically changes the package and you would be subject to any price increases that have been made since your initial booking. Booking it all at once locks in that price and it won't go up if they change prices later. And if discounts come out, you can try to apply them to your booking to get a lower rate.