I have used Regent Air and FF miles through AMEX and there are advantages to both. I weigh both flight schedules and costs before making decisions. The advantage to using Regent Air is that they seem to keep track of your whereabouts and inform the ship of any difficulties. They also take good care of their own regarding flights out and/or accommodations should a situation occur on the ship...like a bad engine that causes you to miss your connections. I have seen the Captain hold up the ship departure for luggage and passengers who are Regent Air and have had difficulties with flights not of their own accord. Hence, we often take Regent Air. Once there was trouble on the Mariner and we missed our post cruise. We had to fend for ourselves to reschedule, whereas Regent took very good care of its own air passengers. We came out whole, but had to scurry for ourselves.

We don't take Regent Air when the air schedule just isn't good for us. When we booked our last trip to Asia, they didn't have any direct flights available for us. We paid a bit more, but got flights to our liking through AMEX two for one. Other times, we use points, but we try to save those for land trips. As others have said, deviation is available for early arrival or later departure at an additional cost. If you change plans, Regent hits you again with another departure cost.

I usually look up which airlines and schedules are going / coming from our destinations and then try to get Regent Air first, especially if they are offering a "deal."

Hope this helps.