SE Asia in 3 months

Hello, I am planning to travel through Thailand, Vietnam, Laos, and Cambodia from approximately December to mid March (3-3 1/2 months). Is this a good timeline? Any suggestions for itineraries or must see places? Should I be diversifying my itinerary, going to some other places? Any help is much appreciated!

3-3 1/2 months is good for that area. You will get to see a lot and not have to zip off to the next place as soon as you get there. I was there a bit later in the year for about the same time a few years ago without getting to Vietnam. I flew into Singapore and went spent a couple of weeks in Malaysia though. For a rough timeline I'd say 4 weeks Thailand, and 3 weeks in the other 3 countries. Cambodia is probably the easiest to do in 2 weeks if you mainly go to Siem Reap and PP. Laos is really laid back and was my favorite. Going there near the end is a nice way to wind down.

I'd recommend starting in southern Thailand for some beach time and working north from there. Actually if I were doing it again I flying into Kuala Lumpar, Malaysia and work my way up. After the beach spend some time in Bangkok and the nearby areas, head east to Cambodia, continue east to southern Vietnam then head north. Leave Vietnam to Laos and then into northern Thailand. You can check for returning flights from Chang Mai otherwise you'll have to go back down to Bangkok.

Once you're in the countries getting around is relatively easy and cheap, but not particularly efficient. It doesn't matter how far your going just assume that each day you're heading to the next town that it will take all day to get there. There's always delays, extra transfers you didn't know about or something. In the end you'll get where you intend to so just consider it part of the journey.

Also, how much money should I plan to spend during this time?

Obviously it depends on you to a degree. What level of accommodation, how much you drink/party, taking airline flights, etc. You really don't see a lot of dorms in SE Asia and single accommodations are pretty cheap less than $10/night, half that in lots of areas. Big ticket items are Angkor Wat ($50 for 3 days or was then), scuba diving and so on. I spent about $1,000 per month, a little over $30/day, in 2007. That was good for a few of beers a day and saw the places and sights that I wanted to. I'd say I was stingiest towards accommodation and transport. It can be done cheaper although you should remember that you are there to enjoy and see the area though not just be there. I'd rather cut a trip a little shorter and enjoy where I am than try to stretch every single dollar. Certainly if you go up to $40-$50/day its still cheaper than lots of other places and you can let yourself splurge when you want to. Once you get your flights and any shots or travel/medical insurance you've already spent a good portion of your total for the trip.

I did a similar trip/ timeline in August-End of October 2008, and I'd say it was just the right amount of time... though there'll ALWAYS be more to see. I didn't see any of Northern Vietnam (crossed the border into Hue and went south) and kind of ended up having to blow through Cambodia, but this was at the end of a year of travel, so we weren't big with the planning. And now I have a reason to go back! But since you're already planning your trip, I'd say:

-Pay attention to visa times/ costs and whether they're multiple entry or not. Then if you want to see something in the middle (went to the 4,000 islands on the Laos side, then went back north to cross the border into Vietnam, when if had been a little more organized, could have nipped up to see that while in Cambodia.) you can figure out how to do it with as little cost but making the most sense on a route.

-Don't stay in Bangkok or HCMC any longer than you need to. They are an experience, and huge and crazy, but there's a lot more way awesomer places to be that don't involve nearly as much smoke and noise. Give yourself a little downtime between things... if you're trying to do too much, then you end up missing out anyway.

-Banking a day to get anywhere is a good idea. Especially in Laos and Cambodia, where the infastructure isn't as developed and the roads are crap. So even if it doesn't look like that far... it'll still take that long. Take overnights whenever possible, you'll be surprised how well you sleep when you're completely exhausted.

The biggest highlights of my trip were also some of the more costly, but were worth the splurge when everything else was so cheap. The number one thing I'd recommend is the Gibbon Experience in Laos. If you're going to Laos, you have to do this. If you cross into Laos to go to Luang Prabang from Chang Mai, it isn't even out of your way. Don't be fooled by the 'gibbon experience' postings you'll see in Chang Mai... Laos is the real deal. Google it, and then look for videos on Youtube. Ziplining from tree to tree over what feels like hundreds of feet, living in treehouses in the jungle... it is completely amazing and I cannot recommend it highly enough. I did do some diving, which was awesome, and Angkor Wat isn't to be missed either, although I think three days was enough to see plenty of temples.

Have fun, you're going at a beautiful time of year!