yes there is such a place - but don't think it is Lamai! You said "not too much" and that wouldn't describe Lamai. How old are the adults? Are you looking to go clubbing?
What time of year are you looking to go?

aparently it's called Samui Laguna Resort , it's in Lamai Beach on Koh Samui.
It looks about right, not near any nightlife but this is nearby(?) in Chaweng, but how far?

Its an easy and cheap journey into Chaweng either by taxi or songthaew- which is like a jeep with benches and great fun! We stayed in Bophut which is about the same distance from Chaweng but to the north. Bophut is great- lovely restuarants and enough good bars to keep most people happy. I will ask for your hotel to be added to our review page and hopefully someone has stayed there!

In the meantime I have found some info for you here

what is the beach like in the Bo Phut bay - my guide book says it's not a very nice beach! not sure what they mean.

I have just uploaded 3 photos of the beach. At the moment you can find them here.
I'm sure you can see it looks lovely! However, to be fair, I don't whether it is just because the sand is so soft but, it does feel slightly muddy underfoot when you go into the water. It is ok though- I should know i kept going in to cool down!! The beach sellers are friendly and not too pushy after the first day. The seller you see in the photo is the pappaya salad lady. Freshly made in front of you and ask for it not too hot- even then it is HOT!! Although there is a lot of accomodation along the beach it is such a long stretch that there often appeared to be hardly anyone there!

have bitten the bullet and booked for the Samui Laguna resort on the Lamai beach. Reasons - we got a good price for hotel accomodation £109 for 2 weeks B&B so we reason we can afford to move ther places if we want and the hotel is supposedly right on the beach whereas our choice in Bo Phut was more in gardens. Who Knows? As long as the hotel is clean and in good repair then it will be OK.
I think wherever we go will be nice and we like to look around so hope to go all over the island and to some more islands (I'm going to post seperate request for info on these!)
Going 20th March so will post hotel info etc when we get back.