Personally, I feel that Coronado Springs is on an entirely different level than Caribbean Beach, almost like a "Moderate Plus." The rooms are more richly detailed (for one, they feature an actual door between the bedroom and the vanity, rather than a curtain) and the resort itself is newer and better kept up. There are tons of fun Three Caballeros references throughout the resort, and the walk around the lake is SUPER lovely and relaxing. My husband and I also really like eating at the Pepper Market. We've admittedly not stayed at Caribbean Beach, but we've walked the resort and were not impressed. The exteriors of the buildings seemed faded, landscaping and theming were not nearly as enjoyable as the other moderates, and half of the food court was closed mid-afternoon.
For the record, Riverside is my absolute favourite moderate resort (possibly my favourite of ALL the resorts), but I wouldn't be the least bit disappointed in another stay at Coronado. Highly recommended!