I love to play on Crater, Chasm Ten, and Windward in ODST, and Unearthed in Reach. It's nice to just run around with your pistol picking off Covenant mindlessly, but also very intense when played in co-op on the higher difficulties. I remember playing Windward on Legendary for hours the first time I picked up ODST, and we'd hide in the buildings to lure the Covies in when the going got too tough. And then there are all those Endure runs... *shudders*