Originally Posted by J.Edward
Within a fleet type I don't think it's that simple. To the best of my knowledge, CO wants more J seats on the 777s to Asia but less on the Europe routes. Yet, they do not have a "Europe/Asia" 777 configuration. I'd wager the reason for this is because keeping the same seatmap across fleets allows for maximum flexibility. Moreover, CO already has the plane to serve second tier European markets - the 752.
A full J configuration for the 737-700ER makes sense for the routes where CO wants to add J capacity but not Y. For example:
EWR-TLV or
IAH-CDG to name a few.
Actually a full J doesn't make sense because it limits flexbility. More J seats is not so much of an issue because you can always bump Y Pax to J if you undersell J and oversell Y ( yes of course PLAT elites get the 1st shot!). OTOH, with all J you are unlikely to sell a Y fare class on that plane just because you have empty seats and Co would probably end up having to steeply discont seats on those flights to fiull them and profit from them. Now some might be made up by more cargo availability because of fewer pax, but the 737 is not known for its cargo capabilities.