Seating and interior: http://www.seatguru.com

Flight selection and availability for your likely routes: airline web sites, flight search sites (hmmm, lots of YVR, would Air Canada be another choice to look at? though United is a Star Alliance partner with Air Canada)

Note: if you go with United or Air Canada as your primary program, you may want to use Alaska as a secondary program to mop up points from many One World and Sky Team airlines, including American, Delta / Northwest, and Qantas.