This Summer, I will have a month off. I would like to see Laos, India, Russia, Cambodia, and Myanmar. Obviously, I cannot see all of them. So if I could choose two, which should I choose, and why?

Having been to none of the above I can only comment on what I have heard.

Cambodia is beautiful and everyone I know who has been there runs out of memory cards for the camera. Lots of photogenic temples and buildings.
Laos people are very friendly and polite, everyone I know who has been around Asia rates it as the nicest place they have ever worked.

Vietnam I have also heard great things about.

Way too much hostility.

all the countries have something interesting to see.

maybe you should take into account the climate.

www.lonelyplanet.com/laos/weather
Southern Laos, on the other hand, is best avoided from March to May, when day-time temperatures break into the 40s and nights aren't much cooler.

You could probably do Laos - Thailand - Myanmar - India, but a month wouldn't leave you much time in each place. I would probably just go to Myanmar and India if I was you (India is huge though you will probably only be able to see a small part).

The reasons are mainly around location - Russia is miles away and you probably should have gone there when you were in Beijing. Laos and Cambodia you can go to another time because they are so damn close and both are pretty small - one of the national holiday weeks you can head to each place and see pretty much everything that's interesting. Myanmar and India are relatively close too, both are pretty big though so would require a couple of weeks each for a nice explore and to get into the culture.

You could do a circular tour of Myanmar in about 18 days. Commence in Yangon by hiring a car and driver. This may sound expensive but it works out far cheaper than you would think. Accommodation is tight now in Myanmar and the driver guide will save you a great deal of money as well as time and frustration. From lakes to hill stations, Bagan to beaches, it's an unforgettable experience. As a further bonus, there is not much Internet connectivity.

Choose Russia - it is the country furthest from Yunnan.

Ha.ha.

No need to rush out of Yunnan Crazy, its a big diverse province with a huge amount to experience.