union afiliation gives no priority when jumpseating. obviously, pilots from the airline you jump on have priority, but if you are cass you can ride the cockpit,so your options are good. remember that if you jump on any airline and a pilot for that airline has bump you off the jump seat, just go ask him to write a pass and let you use the jump seat. i don't know of any case where anyone said no.
remember that some regionasl also have priority over you when going on mainline, again ask the pilot to let you jump and him/her write a pass.
lastly, when pilots write passes, they get charge from their company. offer them to pay the fee they get charge. it could be as much as $20 for regional guys on mainline passes , and those guys don't get pay very good, so them doing you a favor should not have to cost them .
check you squedules from the city you are commuting to/ from and check with the gate agents at your originating airport, they can give you a good idea of how full the flights are and how many jumoers they normally have.
between commuting and living in NY I would choose commuting every single time!!!