The Lion King was predictably good, but its only surprises were visual. I really liked the "grass dance" (for want of a better description).
Betrayal wasn't a play I knew, so it provoked a lot of post-play discussion and analysis between me and my friend. It has a complicated, Memento-like plot structure that runs backwards chronologically, but also sometimes runs forwards. Figuring out what came when, and therefore what lies had been told in previous scenes, made for good dinner conversation. The performances were all solid. Kristin Scott Thomas was well-within her usual range as an upper-class Englishwoman with unexpected fragilities, but the standout was Ben Miles (from "Coupling") as the seething husband.
The Railway Children had to work hard to get past my "I hate adult actors pretending to be children" bias, but it managed to by Act 2. The play wins for "most inventive staging": it's performed in a terminal of Waterloo station, now converted into Yorkshire (you could buy Yorkshire brews during the intermission). When a real steam train charges onto the stage, it's a genuine thrill. TRC was never my favorite book, but the play was entertaining.