I think Krabi may be for you. I have no personal experience of it unfortunately so will let others answer. However, if you go for KS I would not stay in Chaweng. We stay in Bophut, which has some lovely restaurants and bars but which is close to Chaweng- which does have burger joints etc, but also has some fab restaurants
We did a Singapore/KS combination- but in the summer when KS is one of the best places to go weatherwise.

Hi,
I have been to both Krabi [twice],and koh samui.
I will start with Krabi,which i really like.
I stayed at ao nang both times, there is a beach here,but alot of it is taken up with longtail boats. You can catch these boats over to the islands,or to Railey beach[which is fab],fantastic scenery.
The islands are also pretty good,koh poda is my fav,i have spent some great times on this island,just walk around to the back of the island,and you will probably have the whole beach to yourself,the sea is a fantastic turquice colour and so warm and clear.
There are quite a few shops and stalls to look around at night, and lots of great restaurants,but there is also a mcdonalds,although its quite away from the main front .
In koh samui i stayed at chaweng noi beach,which is really nice,just around the headland from the main chaweng beach,yet really quiet,you can walk down the beach to several restaurants set up on the sand.[very pretty and romantic at night]. The main area of chaweng has lots of shops and restaurants,and is a bit busier than ao nang.
I really enjoyed both places,but going out to the islands from ao nang was really fun, there are also alot better trips to go on from ao nang as well.
Have fun
Suzi
ps read my trip report ,on Bangkok ,koh lanta,phi phi and krabi

thanks for both replys,

ao nang- is it on the main, as it looks like an island just off it. i wont get on a boat you see, and not for anything will i try it!

aonang is on the mainland and is fantastic, but to get to the best beaches like railey beach you do need to travel in a longtail boat

thanks, at least i know i can get there without any panics. we have to see if i can brave a boat