Julie,
There are a number of room types at Walt Disney World that can accommodate 5, with varying levels of comfort.
For example in many of the Deluxe resort standard rooms they can accommodate 5. In the room we had recently at the
Grand Floridian we had 2 queen size beds and a very comfortable day bed (converted from a couch).
In the moderate resorts you are going to find a tougher road. Most standard rooms there are rated for 4, though there are some Junior suites available (like at the Coronado Springs) and the
Cabins at Fort Wilderness that can handle 6 with a few different configurations. The cabins, in particular, can be a fun and different option.
Finally, in the Value resorts, you are again faced mostly with rooms that accommodate 4. But with the new Family Suites at the
Art of Animation you really have a great option. You have a separate master bedroom, then two different conversion beds. And with two bathrooms, getting ready in the morning will not take an eternity.
These do give you at least one good choice in each resort category. Review them all and see which matches your needs and budget!
Have a magical vacation!