There may be one older system that has owners rotate between locations under certain circumstances. However, that system (MROP) is small and not particularly cheap, so it probably wouldn't meet your needs.
Instead, there are two ways of accomplishing what you are trying to do:
1) Buy in a resort system that has multiple locations. Typically, such systems give owners a certain number of "points" each year, which then can be "spent" on vacations in various locations. The locations don't rotate. Instead, the owner gets to choose the location, staying at the same one or picking a different one for each vacation.
2) Join an exchange company, such as RCI or II. These companies let you deposit your week into their pool of weeks, and then choose a different week as a trade. There is always a fee for this.
If you own at a resort that has multiple locations, you can still use an exchange company. You might do this if your resort system had, say, 40 locations and you wanted to go somewhere that wasn't one of the 40 places in the system.
Worldmark, mentioned by hudshut, is a system with multiple locations, of the type I described in option 1. I own Worldmark and like it, but it works best for people who vacation in the Western part of the US. Also, Worldmark costs several thousand dollars to buy resale, and there are plenty of nice timeshares under $500 resale.
I also agree with Passepartout that timeshares should be regarded as an expenditure on vacations, not an investment.
. With the possible exception of Lake Tahoe (on the Nevada line, at Heavenly ski area), we would not have been interested in a second visit to any of the PVC properties. It was an affordable and fun experiment, but despite the "location rotation" option, it was ultimately quite limited in choices and in property quality, at least IMnsHO.
