Dp bought an inflatable one - called a Holidoze - much to my initial dismay. But I have to say it has been fantastic, ds absolutely loves it! Its smaller and lighter than a traditional one and takes only a few minutes to inflate.
I much prefer it to the traditional one we had for dd, it never seemed very comfortable
I do also love the idea of the tent ones - this was the type dp had been sent to buy! great if you dont have a lot of space travelling