A Board Game with Simple Rules

My husband, Dave, and I love playing board games. The  game on the top of our queue right now is Power Grid by Rio Grande Games which I received as an early birthday present. We favor games that have simple rules and deep strategy.  To win you have to power the most cities once the end of the game is triggered. It's designed so that the underdog gets priority over higher scoring opponents. This provides a nice balance to the game and forces players to choose between interesting trade-offs. I love the old-school graphics. We just ordered the robot expansion where you can control the turn for up to two "players" to be robots. We haven't tried it yet though so stay tuned! Power Grid increases in enjoyment with more people. We have other games we prefer for 2 players. Which board games do you like to play?