I agree, it wouldn't be worth it to try to change for two nites since the rack rates at the Deluxes are so much and you would be giving up two of your free days. Have you looked into just changing the resort? We were booked at CSR and the difference between that and BWI was around $750 for the week. Not a small amount of money, but to keep CSR and add two nights at BWI at the rack rate would have been $1,000. The difference in price would also be less if you chose WL or AKL.