We stayed in Langkawi for 8 days and loved it. We stayed on Pantai Cenang beach, which is central to beaches, shopping and restaurants.
We were really lucky with the weather - and no jellyfish! I was a tad worried about jellyfish but all we saw was a few harmless ones washed up.
We went on a sunset dinner cruise, a day cruise, hired a scooter one day and a car another. We ate some fantastic food! No where was bad - some restaurants more expensive than others but really great experiences at all.
The island is only small and not party central but that's not what we wanted. We were after beaches and sightseeing which is exactly what we got. Drinks are super cheap (compared to Aust) and meals were definitely cheaper - great seafood!!
One must do is the cable car - I'm scared of heights yet managed it. Some of the waterfalls require a fair bit of up hill stair climbing so prob not great for little kids. So worth the walk up there though - especially if you go for a dip.
The only thing I would give a miss is Eagle Square - really nothing to see there and we preferred the mangroves or beaches etc over manmade. Oh and another tip - ladies bring tissues with you! Most toilets don't have paper :)
Overall a great experience and we'd go back there for sure!!