I mean, apparently you have a bit of a hard-on for flying the big jets. If you care more about flying the 757/767 no matter what, then put in your first bid. You’ll be able to transfer to SEA whenever there is a bid after your start date. Just be aware that if your timing stinks it could be up to a year for your transfer to actually take effect (meaning you have to wait several months for there to be a bid then up to 9 months for the company to convert you). If your priority is getting SEA right from the start then put in the second bid you listed. Your ability to bid to a WB is in no way affected by what your initial aircraft assignment is. It is just a matter of having the seniority to hold it (as well as not be under any seat lock).