Beqa island has a nearby sandbar called honeymoon island that is pretty sick.
If you want a sweet flat water place all to yourself its a go. Only problem is youll be staying at Kulu bay resort - not the liveliest of places, and they might charge you a bit to get out to the sandbar. I'd recommend striking a deal on the number of trips to the sandbar before you book, seems like the resort is pretty quiet, so might be struggling for business (aka ball is in your court)