Choose a location that's easily accessible from a major airport, and with easy access from an interstate freeway. This is the most important one. The fewer flights involved, and the greater ease of renting a fat-friendly minivan or other disability-equipped vehicle at the airport, should be a total fucking no-brainer. The Canaan Valley is not that, and that Burns keeps rattling on about accessibility while wanting to build in a near-inaccessible location that is exhausting to get to and from is just fucking delusional. Also, the closer it is to a major city, the better the access to medical care, which is absolutely something that she should be taking into account.
Look for a place that's already been built to meet the needs of deathfats and disabled people. A former assisted-living facility on the outskirts of a smaller city or town would be ideal, especially one built from the mid-'90s onward. Construction is already ADA-compliant (or can be brought up to current standards). Since Burns wouldn't be running it as a health-care facility, she'd have a lot more leeway to customize the existing space. They've already got private rooms, a commercial kitchen and laundry, a dining room, plenty of parking, and common areas that can accommodate various-sized gatherings—they're perfect for what she wants. In Flyover America they're usually single-story, on or adjacent to a good-sized piece of land with potential for expansion. Buy one of those, redo the interior decor and landscaping, put in a pool, and it's going to cost a hell of a lot less than building from scratch in a remote location.
Choose a location that can fulfill staffing needs, and has plenty of decent, affordable housing for staff who choose to relocate. There is no way she's going to be able to staff her fantasy retreat center from the local labor pool in the Canaan Valley. But if she was within easy commuting distance of St. Louis, Kansas City, Dallas-Ft. Worth, or the Denver or Chicago metro areas, this wouldn't be such a problem.
Forget the hobby-farm bullshit. I know AWFLs love getting all twee with the country life thing, but it's going to require a lot of additional staff and inputs, and the money is better spent elsewhere—such as investing in the local economy by paying local farmers to provide all the veg, meat, eggs, and other food.
Go for comfort instead of luxury. The word "luxury" conveys very high expectations, and finding staff who can actually deliver that kind of experience is going to cost her—assuming they are willing to come work for her in the first place. She can still provide a warm, welcoming, attractive environment that guests will want to return to again and again; it will cost a lot less to do it; and, oddly enough, the guests—most of whom will have never set foot in an actual luxury hotel, and might find the idea intimidating—are much more likely to be satisfied with their experience.
Make it a resort or hotel, not just a retreat center. Requiring guests to be there as part of a planned, organized event, instead of just letting them come on their own, shuts out a lot of the clientele she claims she wants to serve. Some people just want to get away from home, and want a low-key place they can go for a few days' quiet. Or they want to meet up with their scattered friends or family and just hang out together for a few days, without organizing an event. This could be the place for fat and disabled people to do just that, but making them jump through hoops by pretending it's an event is ridiculous. In hospitality, you want to fill as many rooms as you can every night, and shutting the door on the easiest way to do that is just ridiculous.