^^ for Luang Prabang. Laos, in general, makes for a great Asian experience as capitalism and development have not fully sunk in yet. While Luang Prabang is nice, there are great opportunities to travel in other parts of northern Laos, such as Nong Kiew, a serene riverside community set amidst craggy limestone hills. You won't find anything close to a business class hotel in these areas.

Siem Reap may make for a nice cultural stop. Some people plan to spend a week roaming the vast temples which I cannot fathom. One long day was enough for me before heading on. It would look like you could easily travel over land between BKK and Siem Reap, though rumor says a local airline pays government officials to make the road painfully slow and unkept.

Personally, I would recommend Chiang Mai over Chiang Rai. The town offers many diverse day trips where you can ride elephants, trek through hill-tribe villages, and talk to monks on Wednesdays, etc. Chiang Rai could serve as a long day trip and it hosts a few lavish Wats, etc but not tooooooo much else.

In general, you may want to exit Bangkok immediately and leave a couple days at the end to explore the city's bustle. Take a face mask or bandana to protect from myriad exhaust fumes while riding around in a tuk-tuk.

The culture in southern Thailand varies greatly from northern Thailand. Along with pristine beaches, you'll notice more touts and scammers. Personally, I would recommend the western Andaman Sea islands of Thailand over the eastern Gulf of Thailand. Koh Samui (Gulf of Thailand) offers luxury without as many quality beaches. Koh Tao (Gulf of Thailand) is known as a diver's haven, but we preferred diving in the Andaman Sea, especially around Koh Phi Phi (where The Beach was filmed).

In general, I usually recommend northern Thailand for culture, southern Thailand for amazing beaches, and Bangkok only as a layover buffer for flights.

Don't point your feet at anyone and always remember to "smile real big" while there!