We have too many...
1) My townhouse in Alexandria, VA, where we live
2) My SO's condo, which is being lived in by SO's cousin right now (3 blocks from my townhouse)
3) A log cabin in the mountains in WV, which we just bought last summer.
We are early 40s, still working, and I won't retire until I am 57 (need the Fed health bennies). So, we have a lot of time, but this is our general status/plan:
The condo is underwater, so we can't sell it. We'd like to rent it out, but that's a whole different story (the cousin is paying partial rent).
I bought my townhouse 10 years ago, and it is worth much more than I paid for it, even after the downturn. We decided we could buy the cabin now and still retire as planned (once my plans changed when I got realistic about the need to wait for the Fed health bennies).
By the time I retire, the townhouse will be paid off. The condo will be mostly paid off (if we haven't sold it by then), as will the cabin. We'll sell the townhouse, the condo, and pay off the cabin. We'll either move to the cabin, or, if we decide to move back to New England (a good possibility), we'll sell all three and use some of the money to buy a new place to live. Whatever is leftover will be added to our pool of money available for retirement.
However, for planning purposes, all I do is assume the mortgages will be paid off. It's too early to plan for how much money we might have as the result of shuffling the properties around, so to be conservative, I assume the real estate will be cash neutral to our retirement assets.