As a long time theater-goer, I've been to every Broadway house a few times. I'm much larger than I used to be be so I find many seats uncomfortable and I feel like I'm intruding on others seating next to me. I also find that sitting in an aisle seat gives me more room to one side to lean over. Even if he sits at the far ends of the orchestra, there's usually an aisle between the seat the wall (except for the Golden and maybe the Booth). I recently saw Hangmen and I thought I was safe getting a seat in the far end of a row in the orchestra only to find myself pinned between another large person and the wall. Definitely try for aisle seats closer to the center of the theater. Also keep in mind that some seats are arranged at an angle rows may not be entirely straight across the theater floor. I had this problem with a aisle seats at the Beaumont, particularly on the aisle towards the front of the orchestra in sections 2 and 4. Those seats don't give anyone, including thinner people, enough seating space to sit comfortably. The theater with the widest seats is the Marquis, which is a newer theater. Remember that the older theaters' seats were designed at a time when people were smaller, and of course, as a matter of economics, producers want to fill the theater with as many seats as possible.
As far a being tall, I'm not sure how to prevent that traits from being a problem. I've sat behind many tall people and have my theater experience ruined by not being able to see everything on stage in a seat that otherwise had an unobstructed view. If you're going to try to sit towards the end of a row of orchestra seats, perhaps the last row of the theater might be your best bet.