The Neilson holiday we went on (Port Heli) was all about the sailing or windsurk=fing, plus some yachting(and mountain biking if you wanted it). We did the dinghy sailing.
Ds was just turned two and was looked after very weel. It was the end of the season and he was the only one there, but the girl who looked after him was lovely. There was actually another wee girl, but her mother was very protective and ended up not leaving her.
We did have to look after him over lunch (can't remember how long it was - but they co-ordinated with when we go back in from the sailing and when we went out again). On the days when we had a whole day out sailing, they looked after ds all day - that was part of the "package".
Dh and I are also fairly reserved and not "into" enforced group acitvities either. There were a few in the evenings, but we just didn't bother with them.
However, we did meet some nice people - they weren't too "Hooray Henry-ish"
The family rooms in Port Heli were a fair way from the bar/swimming pool area. We had an great wee "aparment": big double bed room with wee kitchennette and fridge and adjoining twin bedroom, where we put up ds' travel cot. He was an excellent sleeper who once he was asleep (usuually in about,ooooooh, 5 minutes maximum ) never woke up again until 6.30/7 the following morning, plus didn't know how to climb out of the cot. Therefore, we were comfortable leaving him and going back to the bar and just checking on him periodically - but I recognise that many parents may not be as relaxed as we were.