what's the one thing I would add?

I wish you could buy a seat covers for the Prius front seats that work with the airbags.I know a lot of people that put standard seat covers but it covers the side airbags and might not make them very effective in the crash, if at all. This is the one accessory you do not see on the Toyota Canada website. I can't find it on any website at all in fact. This is especially ironic since Toyota sells illuminated door sills. While I can tell you the market for covers is a lot bigger than the door things.

What about sheepskin seat covers that run up the seat back but don't cover enough of the sides to impede airbag function?

I think that the covers we put in our Previa just before we gave it to our son may have been like that.

I bought custom seat covers for my gen II, but to tell you the truth, it looks like they just cut out a flap to allow the airbag to work, and then stuck on velcro on so that the flap stays secured. (but the velcro is obviously no match for the power of the airbag).

I have horrible arts & crafts skills and I bet I could convert regular front seat covers to fit the gen III with a razor blade and some velcro.

think about it.