Poland. We loved Krakow and Southern Poland. There are a lot of charming little towns to explore. Food is very good too.
Agree with pp about Turkey outside of Istanbul. We honeymooned there and my favorite parts are taking a blue cruise on the Mediterranean and exploring sunken cities along the coast, and visiting Cappadocia and hiking in Rose Valley.
The Philippines. It doesn't have the tourist infrastructure that Thailand has but its scenery is just as breathtaking. Near Manila there are lots of hot springs. Boracay island has some of the most beautiful beaches in the world. Plus the people are very friendly.
I spent a week in Cuernavaca, Mexico (and Mexico City and near the pyramids) in high school. It is a beautiful city and I'd love to take DH there someday.
South Korea is also beautiful. I also think it is overshadowed by China and Japan, and I wonder if people know really how far they have come in terms of development since the Korean War. Once we hit some more countries, I'd like to go back and visit some of the more remote areas such as Jeju and the eastern part of the country, as all we did was Seoul and the DMZ.
The Philippines was one of my favorite trips we have taken. It was not a trip for the faint of heart - we rode on some sketchy buses and used other unconventional methods of transportation (trikes and jeepneys), because the infrastructure is much less developed than other places. The people were absolutely wonderful - so helpful, friendly, and they speak English which makes travel that much easier. The food wasn't as exciting as many other Asian foods, but it was all very fresh, and the fruit was amazing. The rice terraces in Luzon, about 9 hours by bus from Manila, are popular for backpackers, but not so for your average tourist. They are breathtaking and we felt really good supporting the people who still make their livelihood living there and maintaining the terraces. There are some gorgeous waterfalls and other neat things, like hanging coffins to see in the region. We also did a little walking around in impoverished area of Manila (during the day and without valuables) and didn't feel unsafe in the slightest. The people we're again, very friendly and the shop owners that we bought things from were happy to have us there.
And I agree about Yangshuo and Harbin, China. Yangshuo has some amazing scenery and is just a fun little town in general, but not terribly easy to reach, although you can hire a car to take you there for about $10-$20 a person, so it really isn't too bad. Harbin was so cold, but wouldn't have been as bad if we had been better prepared clothing wise (think walking around in a snow suit cold). The ice sculptures were just insane - basically a small town constructed entirely out of ice.
I'd also really like to get to Laos, which is supposed to be amazing, but like the Philippines really lacks infrastructure making it a trip that requires a higher degree of planning than we've been doing lately.