Have a buddy who travels with Delta for work and uses trips/points to take is XL sentinel in a EVOC XL bag. He says after all is said and done, it's not worth dragging the bike on an airline as there is always some sort of lack of understanding of fees and charges between employees and airports. He now just rents demo bikes or ships through fex ex beforehand.
We're trying to plan a trip to Quebec next summer using our miles on SWA. Unfortunately southwest has the crappiest provisions for taking bikes on a plane and any average sized MTB will never meet the linear inch requirements. We're probably just gonna do the box/ship thing from kinkos to kinkos through shipbikes.com. I can buy three boxes for the price of one EVOC bag and shipping will be cheaper than the $1K + for tickets on an airline that accepts larger bikes, and then still having to haggle at the counter. F@ck the airlines.
https://www.shipbikes.com/