Not a direct answer to your question but a little bit of ATL commuting context. There is a lot of DL nonrev traffic between ATL and JFK/LGA but I believe EWR is easier especially if on own metal.

There’s plenty of history on the ATL MCO commute in the DL/WN forums, if you want to leave Spirit to be an FO on a UAL 737... I also knew a guy who did ATL IAH.

If WB is your goal, focus on comparing the ATL EWR commute to what you have now at spirit. The math may change if a new contract at United improves reserve, but EWR 777 is not as senior as it used to be. EWR 756 has some amazing flying too.