Flying Jib - Longest, Fastest slide on property.
Keester Coaster - Pretty darn fast, and long.
Kidani - Medium Speed, Length, gentle landing.
Jambo - Beginner slide, about 3 curves, and a gentle drop in the water.
Your 7 year old will probably love both. Depending on how adventurous your 4 year old is he or she may be afraid of Kidani's slide or maybe even both... Kidani has a kiddie slide as well and also a kid's splash area. With kids your kids' ages, I would choose Kidani's pool hands down.
Try them both, a shuttle van picks you up in front of the lobby in front of both resorts and runs every 5-7 minutes. Very nice ride. Alternatively, the walk is about 15 minutes.