tekel8,
there is a great little site called seauonboard.com has all the ships of carnival except the new Dream on it. On the side is a list of choices, the first is Cruise 101, the basics, click it, then it has a FYI on cabin selection, tells you a lot of stuff, then when you continue to scroll/read it will get into specific cabins on specific ships. Not only does it give the worst cabins and why, it also gives ideas for good buys on balconys for the money and things like what floor the laundry rooms are located on. The site has a lot of good information for first time cruisers.
I've only been on 3 cruises, 2 of my cabins were on the very warm side one I could adjust very well and was very nice. I brought a small fan in case it was warm and I could not adjust well and it was needed in the Glory. I also brought a small extension plug as they usually only have one wall socket in the room. I love cruising, If I could afford it I would go every 2 months, or go home every 2 months.... haha.