The original singleplayer never seemed to cut it for me. However I played the singleplayer mods AD 1257 (historically accurate as shite for a mod) and Brytenwalda (awesome features) for at least a hundred hours altogether. Brytenwalda especially has some neat stuff like employing your prisoners as slaves in salt mines, allowing you to invest in and build longboats, the ability to entrench and walk around your camp, constructing your own forts, buying land across towns and an awesome setting (Britain around 500 CE).