I want to thank everyone on here and especially @papaflamingo who coached me on how to book flights with Regent Air.
I called this morning and was able to book our flights. Outbound non stop DTW-Rome , my first choice , which was $7000 more than the one stop flights when booking with the airlines, was only $600/pp extra.
(Interestingly, my second choice, which was a one stop, was $900/pp extra).
Flight home wasn't on my list of choices but works fine, other than the tiny puddle jumper from Montreal to DTW. The time and length of flight were the same as my original choices.
However, I was so excited to get that non stop that I didn't check my itinerary carefully enough before I confirmed. On second check I realized that the agent had booked us on the wrong day! 😨
So a second phone call to Regent Air was needed to fix things but the second agent was even nicer and added our frequent flier numbers and got us our preferred seats.
So, again, thank you to everyone on here for your wonderful advice.
And now I'll add my own - check, check ,double check and triple check before you send that confirmation back!