We have had a second home for 15 years and just bought a third. Primary house is in Illinois, which has tax and climate issues. Second house is in coastal New England and is fantastic during the summer, which is the only time we use it. Third place is a condo in Florida, which will become our primary residence for tax purposes. We will keep the Illinois house for several more years and then maybe downsize to a condo there or near where the kids end up (both still in college).
There are definitely maintenance and upkeep issues related to owning more than one place. We do nothing at the Illinois house-lawn, pool, snow, etc. all done by others. The summer house is smaller and the lawn is done by others. We do minor upkeep and repairs, mostly because it's is fun and manageable. The condo has a staff that will take care of minor repairs inside, and of course all outside stuff is done by the association.
The summer house has more than doubled in value since we bought it. The Illinois house value has declined significantly. The Florida place-who knows, but we paid about $700,000 less than it sold for in 2007. A similar but less desirable unit just went under contract for $250,000 more than we paid.
We have been and plan to drive between places (1,100-1,400 miles). We don't/won't keep a car at the summer place but will probably leave one in Florida.
The lifestyle we have had far outweighs any extra costs and maintenance headaches. The summer place has actually been more of a constant for us since we have owned it for 15 years versus only 10 for the Illinois place. The kids have gotten to do many great things, as have we. As a family, we have evolved over the years in the way we use the summer house and the memories are irreplaceable. We expect that as the kids marry and have kids of their own that Florida will also be a special place like the summer house.