We have been to Thailand twice and Malaysia once. I love both of them but if I was pushed I would say I prefer Malaysia.
We stayed at Kuala Lumpur for 3 days and then flew onwards to Penang for 2 weeks. Prices for food in Malaysia are very cheap (I'm going on 2008 prices when we were there). At the Long Island hawker stalls, for instance, our family of 4 cost around £15 with drinks, starters amd mains. Alcohol can be expensive though.
Shopping is also great, weather as you would imagine is hot - we were there in August and everyday it would rain for a short spell sometime during the day but this was fine as it was usually over fairly quickly.
Also loved Kuala Lumpur, the Petronas Towers are just spectacular.

We used KL as a hub for our holiday this year, and we considered Malaysian resorts for the beach element of the holiday but decided to stick with Thailand as we think the beaches are better....we've visited a number of the mainstream Malaysian beach resorts (Penang, Pangkor, Langkawi, Kuantan and other beaches on the East Coast of the peninsula, and Sabah on the island of Borneo).

Penang has a lot going for it in terms of culture , eating and siteseeing, but the sea on the main beach resort of Batu Ferringhi is cloudy and not that inviting. The hotels make up for this with good pools. Langkawi has some nice beaches and jungle landscapes but is much quieter. In fact the whole tourist scene in Malaysia is much quieter than that of Thailand.

Like Thailand eating out is good, with some excellent street food, although some of the hotel food can be bland and disappointing. Prices are comparable with Thailand.

There are also alternative destinations to visit such as National Parks for soft jungle adventure, Taman Negara for example on the mainland, the jungles and mountains of Borneo, hill stations like the Cameron Highlands and Frasers Hill.

We like KL its not as frenetic as Bangkok, but has good shopping, hotels and restaurants and enough things to see for a couple of days. In general Malaysia feels more developed than Thailand with good roads and different multicultural feel but with a moderate Islam predominant. Getting around is easy with lots of inexpensive internal flights, taxis, buses, trains

I have only stayed in Kuala Lumpur and I l;oved it, but in general I think Malaysia is qiute 'staid' in comparison to Thailand.

have to say KL is my least favourite Far East city so far- although funninly enough its also where we found our best hotel
Haven't been to Penang for a long time but like Sunbear said, the sea is not so good for swimming. We did love Penang though and would return

I really enjoy KL not to humid, cheap shopping, safe to walk around, easy to get around and hotels are cheap.

If you want a quiet beach holiday with nice seas to swim in Langkawi is very enjoyable.

I may be travelling to Malaysia in November , is it terribly rainy then? I am thinking Penang or Langkawi.

I'm in Malaysia at the moment! This is our third visit and I definitely prefer it to Thailand, where we've been twice.

We didn't stay in KL this time, just flew straight to Sandakan on Borneo, but it took 30 hours and 4 flights, so probably not a good start for a first trip! KL feels more relaxed than Bangkok to me - I don't feel as though I have to be constantly on my guard against hawkers and scammers in KL, like I did in Bangkok, but we decided to give it a miss this time and head straight for the jungle!

There's not a lot to see and do in Sandakan itself, but it's a great base for exploring from. We spent 5 days visiting Turtle Island, Sepliok orangutan sanctuary and the Kinabatangan river. On a previous visit we stayed near Kota Kinabalu at the Rasa Ria hotel, which has a gorgeous beach, although it may be a bit too isolated for some, as it's about an hour's drive into KK itself.

This time we flew from Sandakan to Langkawi, where we're staying at the Datai for 9 nights. This is probably the best hotel I've ever stayed in - it even beats the Bangkok Peninsula - amazing white powder sand beach, set on the edge of the rainforest with all the wildlife you could possibly want and the most attentive staff ever, all just waiting to cater to your every whim! After a couple of days relaxing, we're hiring a car today to do some exploring. I don't know how I'm going to cope with work after all this!

Elaine

Yes that is a lovely beach a few years ago we stayed just down the beach at The Andaman hotel which had a good outdoor bar just under the canopy of trees right by the edge of the beach. The free guided nature walks were excellent. I loved the sounds of the rainforest at dusk.

Just to update this thread. Lately, prices in both Thailand and Malaysia have been inching up. I think Malaysia is still slightly more expensive than Thailand, but obviously both still very cheap as compared to Europe, generally the west, in fact.

Where Malaysia and Thailand diverge is the degree of tourism. By that I mean that Thailand's tourism industry is very well developed. And you can tell this by the crowded beaches and rather touristy feel of most of the well known resort areas. If you're into the night scene, like hanging out in noisy bars, "starry" hotels and are also keen to ride on jetskis, parasails and what have you, then take a look at Thailand

If it's more sedate, more laid-back, environs you're after, with unspoiled wilderness and plenty of flora and fauna, as well as gorgeous beaches where you can still be the only holiday-makers for miles, then check out Malaysia, especially the East Coast of Malaysia.

Places like Tanjung Resang, just north of Mersing, in the state of Johor, have recently been discovered by those who enjoy lounging by the sea, as well as snorkeling, scuba diving, surfing, deep-sea fishing and sailing. There are also eco-tourism activities on offer. In fact, I spotted snakes, monkeys, wild boars, huge flying foxes, eagles, otters, a porcupine, a scorpion, civet cats and dozens of exotically-plumed birds.

P.S. Shirley, I can't submit URL's but please see my earlier post on the seasonal rains in Malaysia.