The West Bank Cafe is a great place No stairs but it's across 9th ave on 42nd.
Several resturants in area.
This is "Times Square" central. There are a variety of small restaurants on the side streets..43rd 44th, etc. away from 42nd where the theater is located.
The only 'relaxed' option would be the Foundry restaurant inside the Westin, on block up - 0.2 miles from the theatre. Most of the restaurants around of the theatre will be busy and loud.
Sorry if this isn't helpful, but nothing about that area is relaxed. Where that is located might be the most dense area literally on the planet.
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