Because a plug and play hot tub is not hard wired into a permanent outside gfci box it makes it easier to take with you if you ever move. Or if your a renter you can have a hot tub and take it with you when you buy a house or rent another one! Generally plug and play spas are smaller and lighter making them much more portable and easy move, but not having to worry about installing another 220v electrical service at your next home makes the move easier as well.
Chlorine tablets smell bad in the bucket and bad in the spa. Bromine is a little bit better, but I can still smell it on my skin and on my hair hours after soaking. Have you ever opened up your spa cover and detected the strong smell of chlorine? That’s the smell of combined molecules, either chloramines or bromamines. Salt systems are much less likely to produce these foul smelling mutations of chlorine, because after a chlorine molecule is used up, it reverts back to salt, a.k.a. sodium chloride!
In-ground or custom styles are usually referred to as spas. They can be attached or adjacent to an in-ground swimming pool and are often placed near each other as a warm water and cold plunge-type of therapeutic experience. Others are stand-alone hot tubs, but set into the ground or custom built. Some are sturdy portable models (not inflatable) from top manufacturers that are installed to look like they are custom-built in-ground models that can be positioned upon a raised platform, sometimes under a pergola or a gazebo. Others actually are custom built and constructed of the same materials that pools are made of, like concrete, fiberglass, or gunite, along with stainless steel, tile, or copper.
Beach Umbrella: If you are setting your hot tub in the open during the summer, a beach umbrella, or sunbrella, can be really a cool add to the set as you will not have to worry about a harsher sun during the midday and, specially, because is not recommended to get into the tub using sunblock. Many beach umbrellas can be set besides the tub and enhance your comfort and ensure your protection against the noxious UVA rays.