We stay at the Omni and Gaylord Palms at least a couple times a year, and both are fantastic! I give a slight edge to the Omni, simply because it seems to have less convention traffic, and the pool area (with lazy river and slide) is great!
Have not stayed at the Hyatt, but haven't heard anything bad about it.
None of these resorts are more than a 10 minute drive to DTD. Just hop on I-4, go a couple exits east, and you're there.
I will suggest that if you would be happy with any of these three - use Priceline and bid for the Maingate area. They've been coming up for about $70/nt lately, and these are the three most prominent resorts in that zone.
Jim