burau bay is nice and serene for couples 

1)Bayview...Centre of Kuah town..no beach...suitable for shopping trip only.
2)Awana - No beach but there is a yatch lagoon and probably free/discounted trip to Pulau Singa (Crstal clear water)
3) Holiday Villa....Yes lovely beach (Pantai Tengah)....clear water & certain time can catch lotsa star fishes....not so far from Langkawi happening beach i.e Pantai Cenang....

Pantai Cenang has one of the longest beach in Langkawi with all the shoppings, eateries, budget hotels to hi-end boutique hotels & Underwater worlds are there. it is about 25KM away from Kuah town. and only about 3KM South of airport. However the water quality is one of the worst in Langkawi..

Interm of hotels yes there ere plenty especially budget hotels, chalets & etc <RM100/nite

For Hi-end hotels/resort, you can try Pelangi Beach Resort (i.e the starting point of Pantai Cenang) or even the boutique Casa Del mar (opposite laman Padi) (Price >RM300/nite)

For mid range you can try Aseania (however this is not beach hotel a little further inland between Cenang & Pantai Tengah junction) <RM150/nite

For budget, That is what makes Cenag kicking....dozens of hotels & motels to choose from al from RM60 up to RM150 such as:
Sandy Beach, AB Motel, CD lodge, Melati Tanjung, Best star, Delata, Nadia Inn, Legenda Permai, Tg Malie & etc....(U can book this via agents at Airport, Jetties at Kuah/Kuala Kedah)

i stayed in mutiara burau bay.
just use GO HOLIDAY function in air asia.

  U asked for Cenang & Tengah beaches..but u din mentioned Pantai Kok & Burau Bay area 

Mutiara Burau Bay as per the name is located at Burau Bay-lah...i.e on the mid-west of the Island near Langkawi Cable car on the North west of Airport. This area is a littlebit outskirt & about 30KM away from Kuah...the only nearby attraction is the cable car & Telaga Tujuh and luxury eateries located at Telaga Harbour and Perdana Quay.