Our plan:
Retirement is still some 8-10 years away. We are planning to fulltime then.
Bought a downtown Condo and sold the house several years ago. This will be where we land if/when we cannot fulltime any longer. It's near everything and anything we will need, if we are no longer mobile.
We will hire a real estate company to rent out and manage the condo while we are on the road. That'll provide us with additional income to subsidize SSI and 401k proceeds, as well as covering the condo HOA fees.
Over the long term, it's hard to beat investments in real estate, so even if we decide to locate ourselves somewhere else in the future, we'll have the condo to sell at a profit.