Hi Val and Polly,
I have just booked to go to Sani Resort and we have chosen to stay at the Sani Beach Club, as far as I am aware the Beach Club is further away from the Marina, and the Sani Beach Hotel is nearer only 5 mins walk, but from what I have read the Sani Beach Club is 10-20 mins I think you walk along the beach.
The shuttlebus/golf karts are always mentioned in reviews I have read, people always comment how reliable and efficient they are.
Hope this helps
Mariesa x