Welcome to FT eddyd! Assuming that you're short qualifying by Alaska only (at 40,000 miles) and not Partner + Alaska miles (at 50,000 miles)?

Depending on the fare/route you find, paying for a P fare on AS might make sense as it will earn a 75% class of service bonus which means you'd only need to fly ~1471 actual miles. There are also lesser class of service bonuses for the higher economy fares that could pencil out if you're buying last minute tickets that are only a bucket or two lower.

Another way to rack up miles is to double connect through both SEA and PDX, or through FAI if you're ANC based. Alaska's 500 mile minimum per segment can add up. Just make sure the flight numbers are different, otherwise it just accrues as a single segment at direct mileage (the SE Alaska milk run is like that).