It probably is AR, sorry. I don't often use DL miles (and I haven't bought the tickets yet) so I'm sure I got that wrong. I've been in a bit of a frenzy trying to get all this stuff sorted out--I'm traveling to Antarctica and the whole thing has come together in a very short space of time.

I did try doing the AEP-USH portion with Avios and got nowhere. Too bad, because I have boatloads of Avios (including the pile that I just spent to book the PHL-MIA-EZE segments).

Thanks for the info on paying the taxi with a CC, Eastbay1K.