We like places with visible history, where the past is still there to see for those who know it.
This includes much of Europe, with our favorites being Italy, Greece, and France, Ireland, Germany. But also farther afield: Russia was interesting and the Baltic States.
Wild places also make for an amazing trip, most recently we went to Iceland, with its tiny 300,000 population. Iceland reminded us of Alaska on a small scale and has many of the same elements: glaciers, volcanoes, vast empty wildernesses.
Check out some of the photo galleries, then go make your own memories.