Gili Air
The easy anchorage and the restaurants ashore. Usually the first night after the strait crossing.

Charters by day shape
Five and a half to six hours each way from Benoa. The desk plans this as an overnight, and refuses the day-trip version.
The Gili passage from Benoa runs five and a half to six hours each way.
The three islands
Once you are there, moving between them costs minutes rather than hours. That is the whole argument for arriving on your own hull.
The easy anchorage and the restaurants ashore. Usually the first night after the strait crossing.
Turtle snorkelling, and the quietest of the three by a distance.
An evening ashore, if you want one. Anchor off and tender in rather than staying.
What you buy
Departure
Between islands
Where you sleep
Snorkel stops
Honest downside
If all you need is to get to Gili Trawangan, the scheduled fast boat is the right answer and the desk will say so. Charter is for the water between the islands, not the arrival.
Send the start date, how many nights and the party size. The desk replies with the passage plan and the clearance the vessel needs.