Do you have any guidebooks yet? I highly recommend getting guidebooks for all three countries.

Singapore is a very modern city state. It is quite expensive to stay there - check out hotel prices on one of the booking websites such as www.agoda.com It is not a beach destination.

Malaysia certainly has beaches. There are nice beaches on both the east and west sides of peninsular Malaysia. Check on weather patterns. Lovely historic towns in Malaysia worth visiting in Malaysia include Malacca (Meleka) and Penang. Penang is famous for its hawker food.

Thailand is very different culturally from Malaysia. I love Bangkok, funding it much more interesting than KL. And, of course, the food in Thailand is wonderful. If you want to visit all three, you could go by bus from KL to SIngapore (perhaps with a stop in Malacca), then fly from Singapore to Bangkok. Phuket will be rainy at that time of the year, though if a rain shower each day doesn't bother you, you can get very good prices at hotel in Phuket. You can fly from Singapore to Phuket or Bangkok, and do fly between Phuket and Bangkok.

i would skip phuket... bkk has lots to do ans as kathie points out K/L lacks much to do.

I am planning a similar trip to begin tomorrow and found the following link very helpful http://blog.malaysia-asia.my/2011/09/12-free-things-to-do-in-kuala-lumpur-kl.html There are 12 free things to do in KL so you can pick something that interests you.

If you plan to spend more than 15 days in Thailand, you'll need to fly there because Thai Immigration has closed a loophole previously used by many expats to extend their visas by using a land border. If you arrive overland now, you'll only be allowed to stay in the country for 15 days. Arriving by air entitles you to 30 days. Both options are visa free provided you're resident in one of the many countries which have signed up to allowing visitors access to the country without requiring a visa.

If you want to stay longer than 30 days in Thailand, you'll need a 60 day Tourist Visa which you can obtain from any Thai Consulate or Embassy. You can extend that by a further 30 days for 1900 Baht once you've arrived there.

If you want beaches, definitely go to Phuket. It's a really beautiful island with Patong as the party capital. However, there's little else to do there except take a trip to either James Bond island, or Phi-Phi. Both of those can be arranged by your hotel, or by a local travel agent. See: http://www.jamesbondisland.com/ and http://wikitravel.org/en/Phi_Phi_Islands

As for the weather, you usually get short, sharp showers for about 30 mins and then the sun shines again. But because it's low season, hotel prices are much cheaper than high season which is November to March.

Bangkok has its merits, but pollution levels are horrendous. So if you plan to visit the city, I'd say three days is more than enough. But no doubt others will disagree with me.

As Kathie remarked, Singapore is expensive. There are 15 millionaires for every 100 residents in that city state and hotel prices especially tend to reflect that fact.

As for Malaysia, K/L is OK, but it's an Islamic country don't forget and doesn't enjoy the same kind of freedom that countries like Thailand do.