The two coasts have different weather patterns, so think about that. There's a cultural difference as well with Malays predominant on the east and Chinese on the west. We once stayed nearly 3 weeks at the Tanjong Jara resort on the East Coast and loved it. The beaches along there are spectacular. Tioman island has a lot going for it and friends love the Hotel Pangkor Laut on the west coast. Personally I don't like the look of the FS Langkawi.

We most definitely didn't like the MO in KL.