We stayed at the Berjaya, right in the North and 5mins walk from the cable car and Oriental Village.
Great hotel, lots of wildlife and these timber cabin "cabanas" to sleep in.
As for Langkawi....it wasn't as great as we'd expected. Nothing wrong with it, just not inspiring really. The nature walks are great, and a car trip up the mountain in the middle were the highlights.
Otherwise i'd think that Phuket has far more going for it, and that's accessible now from KL or Penang on a budget flight.
Penang I did enjoy, very interesting colonial history, hawker markets for food, great shopping, very mixed Indo-Chinese culture.