Credit as usual to The Flight Deal for putting me on the scent when they shared a fare between PDX and FLL for only $242 with one stop each way in Atlanta. I did some digging and was able to add a second stop in Los Angeles while raising the price to only $250, for a final cost of 3.7 cents per mile. There’s fairly good availability in February.
Alaska Airlines operates some segments between Portland and Los Angeles, but Delta elites are still eligible for upgrades on these routes. And you can credit your miles earned to either Delta SkyMiles or Alaska Mileage Plan; compare the two airlines with this table. Keep in mind that Delta has a new Medallion Qualifying Dollars requirement this year, so miles alone will not be sufficient to earn elite status unless you also either (1) spend enough on tickets, (2) have a Delta credit card and spend a lot on that, or (3) receive a waiver for living outside the U.S.
Need help searching? Check out my three part introduction to using ITA Matrix and don’t forget to check other nearby departure airports. In this case, I searched from PDX to FLL using the routing code “DL DL+” in both directions to require two or more segments. I then sorted by price-per-mile instead of price alone.