Growing out a pixie

That's what I have done in the past, although it always seems to take forever to see any length.  It does keep you from going into mullet territory, though.

Ironically, someone stopped me in the grocery store today to ask me who cut my hair because she liked it so much.  Having second thoughts, now...

I have had a pixie cut for a couple of years now and have loved it, but I am getting bored and am thinking of growing it out a bit.  My hair is super fine, so nothing too long - probably a jaw or chin length bob. 

Obviously, I would like to get through this grow-out period as quickly and painlessly as possible.  If anyone has tips for transitional styles while I'm growing it out, I'd love to hear them.  I know a lot of articles will recommend using barrettes, headbands, etc., but I really don't like to wear anything in my hair.  Also, I am 40 something, so many of those looks just seem too young to me.

So what do you think?  Grow out the entire thing and avoid cutting anything at all?  Keep trimming the bottom until the layers even out?  Trim the whole thing periodically?  I want it to grow out as fast as possible while still avoiding the mullet.  ;-)