I just use Lydia as my storage until I can get in to the secret room at the Sleeping Giant. Once I unlock that room, me and Lydia take a nice walk and bond on our way to the Shrine of Boethiah.
I dunno if I'm the only person that does this.... but I DESPISE bringing any sort of companion with me. just call me greedy but I like soaking up all the xp I can get my hands on. I find it bad enough that I don't get the XP from traps & stuff I use to kill the harder guys. (like activating those spring loaded spike-door contraptions that flings the evil guys across the room)
so the only times I see the companions is when I'm in my house or Lydia is strolling dragons reach etc. and its such a hassle to find them when ya need 'em.
So far the best ideas I've read are the barrels around ward-maidens, and that witch-den. Ill just remember to NOT keep the herbs there as I wouldn't want em to go moldy in that cellar.
But its good enough place for my poor, anguished, wanna-be wood-elf princess.