Originally Posted by
Xandrios
In the past FP elites could upgrade to Comfort+ for free during booking, but this is no longer the case. You have to be lucky to get upgraded, and even more lucky to not end up in a middle seat.
They still offer free C+ to FB Plats if it's a shorthaul flight on a CRJ200 (which DL is phasing out by the end of the year). Upgrades from Y to C+ or F are discounted too but usually it's not worth it unless you're flying US-Canada/Mex for extra XPs.