There are two ways to possibly get an room upgrade at Disney World Resorts. One is asking for a possible free upgrade maybe to celebrate a special occasion. Though this option depends solely on the cast member helping and the time of year. The second is asking at check-in for possible upgrades available, you may even get a lower rate!
First, book a standard room at a Disney resort. Next, go up to the check-in counter with a smile on your face and be very polite. As they are checking you in, ask them if there is a complimentary room upgrade available. In the off season this can happen.
I have done this in two ways. First way: book over the phone yourself, not through a travel agent, and ask about upgrades and discounts. Second: ask at the desk when you check in; ask for a manager if you need to,and be polite but persistent, especially in slow seasons.
An easy way is once you arrive and check in, return to the front desk and explain to the desk that your room is not as nice as you expected. Explain that you wish to impress your visiting inlaws.