i think westin hotel is a better choice,near to Kuah jetty n town. they hav a nice beach which is not crowded. hav visited my friends staying there but beyond my budget. last time we stayed in town itself, City Bayview hotel, about RM 250 per night including breakfast.
near to pantai cenang, a lot of nice hotel like Holiday Villa( book the suites, the beach is very sandy )
in tanjung rhu, hav one of the best beach n sea, there is a first class hotel, but a bit far from airport or shopping or local hawker food

try to look up the web for more info on hotels in langkawi