This may be a little late, but I did want to throw a warning in about the new security setup in the Delta airside. You can't always take the train back from the Delta airside and stay in the sterile area. You'll often have to reclear security to get to the SW airside. Whenever there is an international arrival, they make the return trains (for everyone in the DL airside) non-sterile so that the international pax don't have to recheck their luggage to travel back to the terminal. If there's no international arrival it works like it used to, but it's impossible to predict how it will be set up. Plan accordingly.

And in case anyone is wondering, I've had no issues getting past TSA on the Delta side even if I'm flying out of airsides 1 or 3. The TSA person usually tells me that I'm on the wrong side for my airline but they take "I'm going to the SkyClub" as a valid explanation as to why you're on the wrong side of the airport.