No, they don't really need a guide in any of these places apart, perhaps from Siem Reap. Taxis are general safe subject to the usual precautions. they will not need a driver for most places unless venturing out to a specific site in the country. SEA is a very safe place to travel, my own son spent 6 months there during his gap year aged 18 and loved it. Get them a good guidebook Lonely Planet SE Asia on a shoestring is good.Have a look at http://www.artoftravel.com/ for some sound guidance on safety issues and www.travelfish.org for detail on what to do in SEA.

IMHO Teens would find Hua Hin much too boring. Last time I was there it had turned into a major centre for retires from Northern Europe. There are far more exciting and interesting places for beach time but time of year is critical in making choices due to the various monsoon seasons.

thank you. that is helpful. we can save some money. I think you are right about Hua Hin.

You say these travellers are 20 years old. Those aren't teens, those are adults. They can take responsibility for travelling in Asia as elsewhere -- hordes of young people do -- and will be better off making their own arrangements and having their own fun, which will be plentiful.

It makes sense to have a regular tuk tuk driver in Siem Reap for templing instead of picking up one from the street. Their guesthouse will be able to recommend a reliable one. I'd suggest they stay within walking distance of Pub street as wandering around at night is part of the fun.

Tell them to negotiate taxi prices in advance to prevent any nasty surprises. As other people have said, these are very safe countries. Take the normal precautions that you'd take at home and be careful crossing the street!! While the last may make me seem an old fuddy duddy, the traffic in Vietnam has to be seen to be believed.

Also, its up to them whether they hire a guide for one day at Angkor Wat or not. If they are very interested in temples then it may be worth it for part of the time. It will only cost $20 to $25 a day plus a tip if they think its worth it. There are local guides out at Beng Melea which are very cheap. This is a temple that I'd thoroughly recommend. Both for the temple and the journey.

We had an on duty policeman show us around Preah Khan earlier this year. He showed us carvings I hadn't seen on previous visits and he was very happy with $2. As an aside, our tuk tuk driver had tyre trouble a couple of years ago so we waited by the side of the road while he went to get the tyre fixed. He sent my daughter a text message to say it was more money than he had with him. She walked a bit further down the road to hire a moto. Ended up getting a $1 ride behind another policeman on his motor bike. Its a crazy country but great fun.