The "+" is now the Interface Editor (also under the cog-Preferences menu) and will have an option for extended Quickbars. You'll end up with six total if you hit that, and can then de-active and move them as need be.
Okay, this is really confusing. I figured out how to enable a horizontal quickbar. (When I went into the interface editing, I found the bar and clicked on it, then clicked 'enabled'.
Problem is, it's floating in the middle of my screen rather than directly above my first quickbar. (As I recall, when you hit the '+' sign, it would automatically add a new quickbar and adjust everything to make it fit/look nice.)
I'm clearly not doing something correct here...this is horribly confusing.