Hello tctwhite! I agree with Dave especially being your first time booking if you have a travel agent, use them. They have years of experience and consider things you won't know about or have thought about. Such things as being too close to an elevator, what's above your room or beneath it, all just a few things to be aware of to get the most out of your cruise. You normally don't pay extra for a TA, they get compensated directly from the cruise line. If you book a flight through them you probably will have to pay a fee. If you have been flying and booking your own flights and it works for you this far stick with it. That doesn't mean you can't call carnival yourself and talk to them and get pricing on some rooms.
It doesn't mean you have to book because you call. You can use this information to give to your TA. If you have a carnival book or go online, be looking at the deck plan and if you are given cabin numbers look them up so you know exactly what is around you. WE once got upgraded to the spa deck (top) and what we thought was going to be great wasn't, turned out when it rained our balcony got wet instead of being undercover and the mini golf was above us and we got to listen to golf balls when it was open. Still was a great cruise with minor issues but something we should have really looked closer at
Have a great cruise!