DAL Bases are:

ATL
CVG
LAX
NYC (EWR/JFK/LGA)
SLC

My understanding is that there are pilot positions for all aircraft at every base, with the following exceptions:

777 - Only ATL and NYC
MD90 - Only SLC (Formerly DFW)

Delta used to have pilot bases in BOS, MCO, DFW......they've consolidated in recent years.