I second the votes for Baby Bjorn and the Moby wrap!
The Bjorn is pretty easy to figure out, but is more expensive than the wrap (I owned the "original"). I can confidently say that we got our moneys worth! It's held up perfectly through 2 kids and will eventually be used by my sister for her first child when he's a bit bigger! The Bjorn is good for a child 8 lbs./21 in.-25 lbs. only. However, carrying an 18 lb. baby after an hour, started to strain my back.
The Moby requires some practice, is a tad less expensive than the Bjorn and can be used from preemie to 35 lbs.. If you do invest in the Moby, give yourself plenty of ordering, receiving, and practicing time (the on-line video really helped me out). The Moby gave me more back support than the Bjorn, but is cumbersome to put on (once it was on, I left it on for the rest of the day). Also, I found the Moby wrap to be a bit too warm, which is a complaint for many in the hotter climates (anything warmer than 80 degrees), but good during the cooler months. I also gave my wrap to my sister who is enjoying it now, because her DS is only 2 months old; but I have a feeling she'll switch to the Bjorn for their trip to Hawaii in the spring.
If I had to make a choice between the two for a trip to WDW, just for something to stand in lines with, I'd choose the Bjorn. Happy travels!!:wave: