I hadn't even thought they were pushing for Abby/McGee. The thing is, I've generally gotten the impression from the show that there are anti-fraternization rules in place, so any relationship between the main characters would have to be very clandestine (like Palmer/Lee). And while I think such a thing could be very interesting if they wanted to address the difficulties of co-workers dating, as a light flirtatious romance I don't think either pairing works for me on a canon level.

As you said, it's nice to see McGee grow up and not just be everybody's kid brother for a change. :D