There's a discussion in the comments to Fallout, below, about the balances in the orchestra section of War Memorial Opera House.
I saw Rodelinda again Saturday night. I started in standing room; at the second intermission, a couple of people who were leaving handed me a pair of tickets for M-109 and M-111. These are Orchestra Prime seats on the left and just off the center aisle. They are not far off where Alex Ross and Anthony Tomassini sat for the Doctor Atomic premiere. For that performance, I was in X-105, which is close to the rear, a few seats to the left of the left-hand aisle.
For the first performance I saw of Rodelinda, I was in Z-106 or 108. That is the last row except for the accessible seating row, ZZ, which has four feet of leg room and is immediately in front of the standees. 106 and 108 are a few seats to the right of the center aisle.
For Rodelina, at least, the orchestra/voice balances were much, much better in standing room and row Z than in row M. The orchestra came more to the fore in row M and the voices were more difficult to hear - I theorize that I could hear the voices bouncing off the back and side walls (and maybe the box seat overhang) when I was close to the back of the theater.
Disclaimers: Rodelinda has a much smaller orchestra than Doctor Atomic, of course. And the pit was raised somewhat, as it was for Alcina in 2002. I have no idea how to account for the effects of the raised pit on the balances.