The whole "light bike" thing is for those who race and those who pose imho (and perhaps gearheads and weight weenies). The difference in feel between a 16lb bike and a 22lb bike for a typical rider will be minimal. 99% of riders would be better off losing 6lbs of their own weight rather than throwing money at the bike.
You can get a good steel frame with solid components and put tens of thousands of miles on it without any issue. Or you can buy some stupid CF frame (plastic) with ultra whizzy rims and super-mondo components and have it look pretty in the garage or at Starbucks. I'd rather have a tough, functional bike that is actually comfortable to ride. And there is no way in hell I'd ever own an Al frame, but that is my personal bias. Ti is first choice followed by steel. After that...I'm not interested.
Got a bunch of money and want the coolest bike ever? This would be my choice:
http://moots.com/?#/product/bicycles/road_+_speciality/comooter/