Seconding the endorsement for Mountain Lion. It can act very traditional if you want it to, but if you're willing to go outside your comfort zone, it can really change the way you use your computer in great ways. Like I keep my email program in a full screen that lives . . . it's kinda to the right of my desk top. And whenever I need it I just do a big, four-fingered swipe to the left and it swoops in. And then you swoop it away again. 'Tis like living in Minority Report * g *