We booked a one way through Royal Caribbean in 2017, we looked at what flights were available and told them what we wanted as they can offer you flights that go on a longer route but if you know what flights you want you can tell them then phoned and it was a reasonable price but you have to wait till the flights come out.Our journey was from Glasgow to Newark then Newark to Fort Lauderdale with luggage with United and it was £674 for both of us.
This year I phoned and their price again was reasonable but I had some avios and managed to get a cheaper flight from Gla to Lhr then Lhr to Mia with luggage for £600 for us both.