I am booked for 7 nights at CSS but am having second thoughts about spending some time at CTI. Should I split the trip into two with 3 nights at CTI?

I'd like some physical activities for part fo the trip and CTI looks more active....

Is this easy to change on the reservation or is a new resrvation required?

Is it easy to transfer from one hotel to the other? Which should we do first? CSS or CTI?