I took a pouch sling with my DS when he was 6 months old, and a ring sling at 10 months old.
I prefered the ring sling, just because I found it easier to distribute his weight across my back. It's made of cotton, so wasn't too hot either, especially considering we went in May. He slept in it, and I was able to pull the "tail" up to cover him if we were out in the sun. He rode a number of rides while in it, and slept through several as well, including Haunted Mansion!
Looking forward to being able to "sling" around the next baby, since DS is now too heavy and too busy to be bothered with the slings!!