For folks looking for non-F3/F7 motive power to head up their El Capitan train, Lionel's upcoming Santa Fe ES44's might be a good choice for modern power.
Unfortunately Lionel only catalog'd these in two road numbers, so folks will need to double up on a roadnumber (or two) if they want 3 or 4 powered units. Not a showstopper though, since the ES44's aren't prototypical for this train anyway. They'll still look impressive!
Another cool option for modern locomotive configs would be the Atlas-O Santa Fe GP60M-B-B-M (from the mid-2000 years) with 3 or 4 powered units depending on the number of El Cap cars in your train.
David