Do you have any experience with them? Risk would be the obvious example, but that's probably at the lower end of the complexity scale as far as tabletop strategies go.
I hadn't tried anything more complex than Risk until a few weeks ago when some of my new coworkers lured me over to the dark side and we played Dominion and Elder Sign. Which were both fun (Dominion more so) but complicated (Elder Sign more so). Tonight we joined up with a few new recruits and played the Game of Thrones board game. It seemed incredibly complicated at first, but it wasn't too bad after you got into it. Sadly, by that time, half the game had already passed, and a few misguided attacks left me stranded at Pyke with my Greyjoys. Accurate storywise, but not so great strategically. Next time, though! It was a really good time.