FlyinHawaiian

I normally look at the seat map before booking to note the availability of window or aisle sets in the C+ (shorthand in this forum for Comfort Plus) and also the general cabin. As a PM, you can pre-select any open seat in the main cabin that meets your needs and ask for an upgrade into C+ if you think there's open window or aisle seats. Once confirmed into a seat, remember that seats do open now and then as other passenger's travel plans change. A lot of changes and desirable C+ seats tend to open up around 100 hours before departure for domestic flights as upgrades start to clear. I check seat maps often until I am in a seat I am happy with (and then check to make sure I haven't lost it before departure).