Depending on my mood, I'll carry a laptop bag one day and then use a laptop sleeve the next. Sometimes it depends on how much is already in my purse and whether the sleeve and laptop can fit in there. Some days I curse my sleeves for making my bag so heavy, and some days I don't want to carry a whole extra bag.
One thing a girl can't complain about: the variety. You can go custom, like with this sleeve, and laptop bags in general are starting to branch out in designs, like this bag from J. Crew. I can't decide which way I prefer to tote around my laptop, but can you?
And don't get me started on letting it go naked!