Asia - asia itinerary

my girlfriend and i are headed to asia in july/aug 09 for 3 weeks on our honeymoon. we fly into beijing and out of seoul. we are trying to put together a travel plan. we plan on booking flights to go between coutries. we would like to spend time in/around beijing (see the wall, temples, ) then we would like to travel to thailand and vietnam (we are looking for a beautiful beach in either location). we are generally do-it-yourselfers and like to be off the beaten trail. we would love to take a cooking class, etc

any suggestions for itineraries, beaches in vietnam or thailand, means of travel, etc would be greatly appreciated.