Maura,
You are looking at two moderates and one value hotel, so first you have to decide which best matches your budget. The Pop Century is a great resort, but of course the higher cost moderates that you list have more amenities.
If the added expense of the moderates is not going to bankrupt you, I strongly urge the move up. The jump in amenities, as well as room size, is well worth the money.
Now to decide between the two Moderate resorts. Often you will see me recommending the Port Orleans French Quarter to many guests. But in your case I would opt for the Caribbean Beach. Why?
- Pool. I think that the newly refurbished, pirate themed pool is a fantastic feature
- Resort theming. A 4-year old is going to love living in the land of pirates
- Pirate Rooms. At only $25 more a night, they are a fun escape!
- Central Location. You are actually more centrally located here. Closer to all but Downtown Disney
Final point. Remember that all of these are great choices. But my order of preference for a family with a four year old would be Caribbean Beach, French Quarter, then Pop Century.
Have a magical vacation!