If you want an easy way to travel around this region of SE Asia can recommend Asia Pioneer.
Lam organised our tour, and it was just great to be met at each airport and have a private guide with good knowledge of the area at each of our destinations. The trip basically went without a hitch.
If I were to do this again though I think I would probably allow more free time – as we were all pretty tired at the end of each day. So be sure to read your proposed itinerary carefully so it suits your individual needs.