See an independent newbie friendly WELL REVIEWED provider first before you take the so call "training wheels" off. Also see someone with a donation you are comfortable with. A newbie friendly provider can show you things and help you get comfortable with the hobby. After all you don't want to spend $$$$ your first time out and come away feeling cheated or that you were not more assertive in telling the girl what you like. Generally first time hobbyists can be a bit shy and reserved (I mean I was with my first experience in the hobby).
As far as your list, all three are good choices however Bethany has the smaller donation (I think $$$) than the other two (unless her rates have gone up). All three provide PSE and Courtney is probably the dirtier, up for just about anything, out of the three.
If you book them, use an agency. Bethany and Courtney can be hard to reach through other avenues.
Pamela Peaks, TLC, My Platinum Provider are the agencies that work with the three you asked about. Hope you have fun!