This. Unless there's an unexpected flight delay with no empty seats on other Southwest flights to your destination, you won't have enough waiting time to make a lounge visit worthwhile. It's rare that I wait at the gate more than 15 minutes before boarding starts.
A few years ago US Airways had a lounge in Terminal 1 at LAX. It was less than a 2 minute walk from Southwest's gates and I had a membership, but I visited the club for only about 10 percent of my trips. I suppose I could have intentionally added time to my trips to hang out at the club and utilize my membership, but that option seemed silly.
Well, that said, a lot of the itins I've been looking up seem to have 1hr plus connections at various airports including Den, Houston and Luv