Hi Richard!
Thank you for bringing your question to the Disney Parks Moms Panel!
To get the most accurate answer for your particular reservation, I suggest that you call
Disney Resort Reservations at 407-939-1936. They can provide you with an exact amount.
As a general rule, there is no additional charge on a room unless there are more than two adults (18 and up) staying in that room. If you will be having more than two adults, Walt Disney World moderate resorts currently charge $25 per person above those first two.
Disney's Caribbean Beach Resort is a great choice! I really like how it makes you feel as if you've been swept away to a tropical paradise, especially after a long day in the parks. To me, it feels like two separate vacation experiences.
I hope this helps! Please let me know if you have any other questions as you plan.