One of our options to get from SEA to ONT is Delta first class, with a 737-900ER to SLC, and a CRJ-900 from there. $210. Both planes have first class seating, but how much of a difference (positively or negatively) is there in FC between the CRJ and, say, the 737? We'd likely sit together, on the right hand side of the plane.

Alternative is to take Southwest, for $134 (plus $13 Early Bird fee), going through SJC. Not first class, of course, but on 737s both flights. A bit shorter travel time on Southwest due to shorter connection time (1 hr. vs. 2 hrs.), though we could apparently get into the Delta Sky Club at SLC with an Am Ex Platinum Card.