As a 75k, who RARELY gets the 5 day prior to travel upgrade, I never pay for an upgrade with either cash or points. It's not worth. Granted if you need a wider seat or want the free food and drinks it may be worth it on a personal basis, but not to me.

If you have any priority with Alaska book an exit row aisle and hope for the best. And if you want the upgrades and you're a top tier flyer my friends tell me United 1K is the place to be because they score a lot of upgrades 5 days out not to mention guaranteed systems wide upgrades.