I've been in the marina since 95' prior to that 4 years over in Balmaha and a couple launching from Balloch (now on my seventh boat).
Probably everyone will have their own reasons for using CH.
1/ Fresh water,so much less maintainance.
2/ Walk on pontoon with 365 days of shore power. Fridge and food lockers always stocked. spare clothes, my beds are always made up and heating always on just a peep so when I arrive on the boat i'm ready to go within a few minutes.
3/ The current standards of the bars both in the hotel and at the marina are expensive but exellent. I suppose you have to think about where you have your drink and not how much it costs ( Well not too much). If the food and drink was cheaper it would be much busier and although they could do with just a bit more atmosphere I for one like to go there to get away from my busy working life and relax for a few hours.
4/The weather and lack of tides means that the loch is useable all year round and is an extremely safe piece of water when you know your way around.
5/ I do entertain on the boat sometimes and guests are always very impressed by the marina and although we are very used to it, generally my friends are not and they feel special for the day. ( Although next time i'll check that Johns not on his sealine and set my buffet up on his saloon and pretend its mine for the day
)
6/ Fresh water pipe at the rear of the boat.
7/ The hotel grounds are stunning in the summer and we often walk round them and I cant think of any other marina with a golf course on its land.
As for value for money, that will be contentious as we don't get what our money prommised us ( security for one) but i have a friend with a caravan up north who pays the same as us and his facilities not even close. I use the boat as a bolthole instead of going abroad more often where a weekend in Itally can cost £1500.
Cruising with any boat in the clyde can get pretty dangerous very quickly when the weather turns but on the loch you never feel unsafe and there are loads of havens if you have to get out of the weather quickly.
I'm sure there's more but its early and I need to get on with some work.
Good question though look forward to the other answers.