We are going on a Carnival cruise for our honeymoon this august. We are trying to decide if we should go on an eastern or western caribbean cruise?
The Caribbean in August??? Eeewww, yuck! If a hurricane does not get you, the humidity -- very oppressive -- most assuredly will. The time of year to go to the Caribbean is from November to April, when it's much less humid and there's little danger of hurricanes.
If I were booking a honeymoon cruise in August, it would be either to northern or western Europe (the Mediterranean is also oppressively hot at that time of year, so most businesses actually close for the entire month) or Alaska. If you are seriously concerned about price, consder an "Inside Passage" cruise to Alaska from Seattle.