I've got a pretty good idea what Bezos has in mind for a vehicle (Gary flagged me on this one.) A VTOVL first described in a paper written by Jim French along with Robert Staehle called "Crew Transportation for the 1990's" (God, I feel old.)

It was written up back in 1989 in issues 30 and 31 of the World Space Foundation's "Foundation Astronautics Notebook."

I've got the papers right in front of me, but as far as I can find, nothing on this is online. The vehicle proposed back then was a biconic mixed-mode LOX-Hydrogen-RP1 system carrying seven people, and with a combination of RS-27 and RL-10 engines.