There are many benefits in using a dry rack storage facility:
It’s especially popular in warm weather locales. However, its available everywhere.
Here’s an excerpt of an article that appeared in Boat US a while back covering the pluses and some drawbacks.
First, ease of use. You call ahead to have your boat brought down and even fueled. Then you arrive, hop in, and go. When the day is over, you return to the marina, dock the boat in the designated area, and leave. The marina washes it down and puts it back up on the rack.
Second, it may save money. Since you don't have a trailer, you're not spending money on gas, launch fees, or upkeep on the trailer. Also, because your boat isn't sitting in the water, you won't have to clean off the marine growth or bottom paint the hull every year.
Third, it keeps your boat in better shape. If your boat is sitting in a big steel barn and not constantly being bombarded by the sun's UV rays, you are lessening the possibility of gelcoat damage. However, keep in mind that if your boat is in a three-sided shed or a rack with just a roof, some sunlight might get on your boat.
Fourth, it's good protection for your boat. Most buildings have security measures like electronic security systems to stop vandalism and outright boat theft. Many of the newer buildings have fire suppression systems from sprinklers and even synthetic fire retardant foam systems. Also, many buildings in hurricane-prone zones have been built according to local hurricane codes. If you keep your boat in a hurricane-prone area, check to see what kind of protection the rack facility offers.
Fifth, it provides alternatives to keeping a boat and trailer sitting in the driveway. Due to homeowner association by-laws or city ordinances, some small boat owners can't keep their boats in their driveways. In addition, dry stack storage is good for owners who find themselves being kicked out of marinas to make room for larger yachts.
Last, it may be environmentally better in some circumstances. According to Delaware State Parks' Indian River Marina, dry stack storage "Minimizes need for dredging, minimizes water quality and flushing concerns, and reduces the amount of contact time between pesticide-containing bottom paints and the water."
Of course, as with everything, there are some downsides. Most places only allow you one launch and retrieval per day. That launch time can get long if the dry stack is extremely busy that day. Also there usually isn't any place at the facility to park your boat in the water and use it overnight. Also, you can't just show up at the facility and tinker around on your boat. Most dry stacks don't allow boat owners to work on their boats in the facility.