My initial reaction was to say Something Rotten, which I loved. But considering you can see it on tour, and you're seeing after a 4h play I might go with an Act Of God. I haven't seen it with Parsons last year, but I love Sean Hayes and would have made it more of a priority if he had been in it then. I love the clips I've seen of him in LA/SF, and compared to clips of Parsons, I find Sean funnier.
It might be a more relaxed way to end the after the marathon with Long Day. Something Rotten is so hilarious, it's quite a lot to take in the first time around. My friend was so overwhelmed that she didn't really love it until she saw it a second time. The jokes/laughes come at such a pace you don't really get a brake for 2.5 hours, and I'm not sure I could handle it on a 2-show day, let alone after an intense 4h play.