Check on Sutter Stockton garage. Probably the closest, and most reasonable. The Donatello Hotel (1/2 block) did offer theater rates, but check with them first as I am not sure if they still do. Enjoy! I love SF Playhouse.
The theatre is pretty close to a lot of paid parking lots including the union square garage and the post and mason garage around the theatre's corner. A little further near the metreon on 4th and mission st is a very popular paid lot as well. Hope that helps. Enjoy the show!
There's a garage about 1.5 blocks away.
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