2-2 on the airport line makes more sense I think. Wider aisles still leaves standing capacity (not a big deal on a 29 minute max ride, compared to 50 on the southeast), and also makes the car navigable with luggage. Bike spots are a no brainer, and also double as luggage space for those big bags (assuming we won't have intercity-train-style luggage racks in the cars).
2-3 would be better to Boulder - more seats for the long ride. Plus, those friendly Boulder liberals are more likely to sit with strangers on the 3-seat side.