The slide is located at the main pool, near Olivia's and main check-in. For that area of OKW, be sure to try to book in the "Near Hospitality House" category, it is a separate booking category, same number of points. The Near HH category is buildings 11 to 14 and 23 to 26.
There are 5 bus stops throughout the resort, the one for Hospitality House is the LAST stop on the circuit, except for the internal/DtD bus, which stops there first AND last. There are 4 pools (the main pool & 3 large quiet pools) in the resort. All the pools have a sandy children play area and hot tub. While OKW can feel spread out, it is really about a 10 minute walk, at most, from any outlying area to the Hospitality House area. Also, you can hop on ANY bus, and it will drop you of at HH, as it is the last stop. To get back to your room, walk over to the Peninsular Rd stop (near Bldg 26), and board any bus, as it is the first stop in the circuit.
There is also a small sauna room built into the base of the OKW Lighthouse, near the main pool.
The bus stop are, in order,
Peninsular Rd
South Point
Old Turtle Pond
Miller's Road
Hospitality House/Cove Road