Sue
I have stayed at the Merlin Beach Resort and it's a nice hotel with lovely pools... the small beach is unswimable due to too much coral. However, it is isolated (you may like that) and a 10 minute tut tut ride to get into Patong or elsewhere if you choose to eat out of the hotel. There was only one restaurant nearby but was destroyed by the Tsunami and I'm unsure if it's been rebuilt.
Check out tripadvisor and asiarooms for hotel reviews to help you decide.
Good luck spending your vouchers.
Cheers Geri