Delta really does stink on award availability, but I will give them credit on having one of the best products in domestic F on the 757 over their competitors. The AVOD is great, wifi works well, and the interiors are clean and fresh looking. I far prefer doing a trip on a DL 757 over any of UAs domestic fleet except in the case where UA has an INTL plane on the route. I've spent a whole weekend doing MRs on a DL 757 in F and would do it all the time, since it's a nicely equipped plane.
I can't wait to see what they end up doing with the 747 and am glad to hear they're making an investment on these birds in particular. I've never flown Y on a 767 or 777 of Delta's, but AVOD is a great addition to any plane. The addition of F to the CRJ-700s is definitely needed and a good competitive move.
With the NWA 757s those planes just look tired as hell. New seat covers and lighting will be a help, but I think a complete interior overhaul is needed. I can understand why they'll take small steps for now on those planes with an uncertain future and when replacing them with 737s may be on the drawing board. Now I want to know what will be done with the A319 and A320.