Here is a list of all hotels in Bali with water slides.

Nikko Bali Hotel, Nusa Dua - 30m water slide (adults & kids)
Westin Resort, Nusa Dua - 12m water slide (at kids club)
Grand Hyatt Bali, Nusa Dua - 50m water slide (adults & kids)
Ayana Resort, Jimbaran - Two water slides
Hard Rock Hotel, Kuta - Water [...]

AirAsia is offering a super deal for travel between Perth and Bali.  According to the airline’s website, “you pay the fee”, and they will “fly you for free”.
Airport taxes and charges from Perth to Bali are AUD$77 which is all you will have to pay.
The booking period is from 5th May 2009  - 10th May [...]