I just looked at my visa from our Vietnam trip in 1999, and it was a single entry. We went from Saigon to Siem Reap and then to Bangkok, so I did not need to reenter. The visa has a stamp on it that says used, so I suspect that you will need a multi-entry visa to go back to Vietnam from Siem Reap.

I would not take the malaria pills for only the two days in Angkor. You have to take them for a very long time once you start. I am really bothered by mosquitos, and I remember using something like Cutters or Deep Woods Off and not having a problem. There is no problem in the cities, but you could need the repellant if you take day trips from Vietnam, particularly to the Delta. The malaria mosquitos reputedly are only out from dusk to dawn.

Also because you are not going to be spending time (i.e. staying)outside of cities, other vaccinations are probably not necessary. Of course, I think Hepatitis A is now recommended even in the U.S., and if you haven't had a tetanus shot in 10 years, you should do it no matter what. Do you have a travel clinic near you? In Chicago, Northwestern has an excellent travel clinic and provides not only vaccinations, but recommendations based on the information you give them about where you will be on your trip.

I am looking for the other information I told you about for Saigon, and will get it to you within the week.

Lisa