The former British colony basically consists of one part located between Thailand and Singapore and another part (Sarawak) on the island of Borneo. Being a tropical country with substantial industry, you can experience everything from tropical rainforest, beautiful beaches (on Langkawi island), a diverse capital (Kuala Lumpur) up to the often criticized palm oil monocultures.
I suggest to start with a visit to Kuala Lumpur and its atractions, the Petronas (“twin”) Towers. Visit some of the lush shopping malls and the bustling ancient Chinatown with its small shops and temples. Subsequently, you can spend beach holidays on an island like Langkawi or explore other provinces. Lifestyles in the country vary from “liberal” in tourist detsinations to more religious conservative attitiudes (e.g., in Terengganu), and so some upfront research is recommended in order to behave properly.
I can also recommend to take the train from Kuala Lumpur down to Singapore, this offers you some good impressions of the different vegetation.