Get the auto! I had a CLK320 auto before I got the IS250 and thought I was sick of an automatic so I opted for a manual. The manual gearbox in the IS is awful, I regret the decision to this day.
Bought a 2007 IS250 yesterday. Picking up Tuesday when I'll have to hand over my 2000 Mercedes CLK320. Before that I had a 2003 Mitsubishi L200 and a 2000 Ford Fiesta before that.