advance purchase of airline tickets; when is best?

Hi and welcome to the forum!

Don’t look for two separate one-way tickets. Look at open-jaw tickets, also known as multi-city flights. Check Google Flights, Kayak, and other aggregators but buy directly from the airline.

We are doing this tour the end of September. We either go out of San Francisco or Seattle, same distance for us. I booked our flights out of San Francisco on BA because it was cheaper than Seattle. I wouldn’t wait any longer to book your flights, right now they are inching up in price and are about $100 more than they were when we got ours in January. Check Google Flights for comparing airlines and flights.

Edit: And I agree with Kenko, I started checking on our flight periodically because of what’s happening politically. The fact the price of our tickets hasn’t gone up much “could possibly” mean that they aren’t selling seats on our flight.

I also think you should buy now. The airlines are seeing decreased demand for European flights overall and likely will be consolidating their flights. Once the airlines determine which flights they will be cutting, the remaining seats on the flights they keep will rise in price www.Skyscanner.com is showing excellent multi-city Delta flights from Seattle to Reykjavik on August 24 returning from Dublin on September 10 for $616.
One connection of less than one hour in each direction.
That’s a great deal.

Always book MULTI CITY tickets. Not ONE WAY.

We always get the best price on opening day which is 330 days from your return flight home.

Thank you for your responses... I will get right on this. It is comforting to be part of a community of like-minded folks who will take the time to share their experiences.

I always do as ChinaLake67 suggests. Buy 330 days in advance of your return date and stay away from one-way flights. The price of a one-way ticket is much higher than 1/2 of a roundtrip. If you ask IcelandAir nicely, they will combine a feeder flight into Seattle on Alaska Airlines which make the entire trip "covered". I booked through a consolidator a few years ago and flight changes were miserable to deal with - if possible, stick with one airline, dealing directly.

This year might be an exception, as flight bookings are way down due to the lovely trade war, and we might be in a recession by August.

Buy 330 days in advance of your return date

There aren't anywhere near 330 days between now and September 10...

I am a little curious where people are looking at flights that the round trip or multi-city option is always cheaper for them than one way. Maybe it has to do with where you're traveling from or specific airlines, but I often find the fares are exactly the same whether you book one way vs round trip, and multi-city ends up being the most expensive for me when I've checked. Maybe that's because I don't live next to a really large international hub so I always have to book more than one flight, but the algorithms aren't great at finding me a good deal.

My real piece of advice is to clear ALL COOKIES on your browser before you make your purchase! Airline's websites sometimes use cookies to identify that you're shopping for tickets and the prices magically go up the next time you look. If that's the case, the prices go back down once you clear cached cookies. It's happened to me before and clearing cached cookies saved me a couple hundred dollars.

If you look at the airlines fare codes, many of them are tied to length of stay. If you get independent tickets from independent airlines, you fail those codes and will usually pay more. Two one way tickets (using the multi-city method) will trigger those fares. In the case of BA, flying to Aberdeen is a lot cheaper than Edinburgh, while the return flight is cheaper from Edinburgh or Glasgow. It definitely takes some experimenting. Day of the week is also a variable. The suggestion to clear your cookies (or use a different device or browser) is a good one.

We end up on IcelandAir more often than not because we arrive in Seattle from Medford, and IcelandAir puts us in Scotland early in the day (11am). They also let you book extra legroom at the time of the reservation. We live with the sketchy food/drink service and carry-on our own food. Also, we usually bid on the upgrade from Reykjavík to Glasgow since it seems to go for the minimum bid, which improves the cabin service immensely. I'd fly BA except the early flight doesn't connect with the feeder, putting us in Scotland at 5pm or later, too late to go on to another island destination. Last time we flew BA, Alaska Airlines shuffled their times and it nearly blew up our entire trip. Avoiding Heathrow is another benefit of not-BA.

I often use Momondo.com to find flights, then book through the airline. We only fly long-haul one trip per year, so my advice should be taken with a grain of salt.

I am a little curious where people are looking at flights that the round trip or multi-city option is always cheaper for them than one way. Maybe it has to do with where you're traveling from or specific airlines, but I often find the fares are exactly the same whether you book one way vs round trip, and multi-city ends up being the most expensive for me when I've checked.

@Claire - it depends on the airline. Many of the major airlines charge significantly more for two international one-ways than for a multi-city ticket. For example, i just looked up the route for my next trip (Washington Dulles to London Heathrow / Dublin to Washington) on United. A multi-city trip is $891. Two one-ways are $584 (IAD to LHR) plus $1162 (DUB to IAD) for a total of $1746.