IF you are convinced that you want to go to Orlando, then I'd troll the Disney sponsored sites, the packaging available from the provider will give you the best all in one stop coverage of lodging, tickets etc.
This is good start, http://www.magicalgetaway.com
If you want to roll with the punches and cobble together a package then try Expedia, Hotels.com or Orbitz for lodging. Tickets for events can also be bought around the Orlando area from 3rd party vendors.
Gatlinberg... I used to go there when my wife was at Miami, we'd rent a cabin and do a LOT of hiking, everything else there is awash in cheese IMO, but the time you are targeting will also probably give you some nice color at the higher elevations, so the time of year is right, but I'd look for a cabin because that's way more romantic and peaceful than a town full of tourists and their kids.