hi...
here are a few suggestions on what to do in Malaysia...
1.) Jeram Besu (Located in Pahang state, for challenging white water-rafting activities)
2.) Cameron Highlands (Located in Pahang state, nice cool place, check out link for more info. http://www.cameronhighlands.com/ )
3.) Bukit Tinggi, (Located in Pahang) - http://www.cuti.com.my/Sub/Pahang/guide_bktinggi.htm
4.) Taman Negara (Located in Pahang) - oldest tropical rainforest (worth the visit if you are into nature)
5.) Kuala Lumpur - shopping (KLCC, Mid Valley, 1 Utama, Pavillion, etc)
here's a website about the many places in Malaysia that might be useful to you.. http://www.cuti.com.my/guidehome_malaysia.htm
a few recommendations of other places in Malaysia if you have the time and not raining season.
1.) Club Med Cherating (Pahang state)
2.) Sipadan Island (Sabah state) - great place for diving
3.) Perhentian Island or Redang Island ( Terengganu state)
4.) Mount Kinabalu (Sabah state)
hope it helps...have a nice holiday in Malaysia