i visited malaysia a few yrs ago. the cities i visited were kl and langkawi. as far as hotels are concerned, in kl, we stayed at the mandarin oriental which is right next to the petronas towers and klcc. i personally found the location to be amazing and the hotel was great. in langkawi, we opted for the four seasons resort which was only a week old then. it is one of the best hotels ive ever stayed in.
personally for me, genting is highly avoidable. i didnt like it much. we went there only for the day. we also visited sunway lagoon in kl for a day to use their water park. that was also nothing great.