Sat front row at the symphony...

@nicotico

Very wide range or even more omnidirectional speakers like Ohm Walsh would fill that space more like live instruments than most more directional designs. It’s what they do and why people like them. 

Yes, very front row is good but not best unless you like wide soundstages or looking up violinists' armpits.

I would say 7 to 10 rows back.

And although OP specifies an orchestral concert, in a piano concerto it is good to side halfway to the left, on the 'keyboard side' so you can watch the pianist working.

I once had front row center seats to a Peter Tosh concert.  Not only could I feel the intensity of the show, I could smell it too! 😎  There is something to be said about sitting so close.....you really feel as one with the performers.  I can only imagine a symphony to be much more intense.

Back in 1982 Richmond Colosseum, the summer home of the Chicago Symphony Orchestra. is incorrect the summer home for the CSO is Ravinia Festival in Highland Park Il, Glad you enjoyed the show they were probably in town for a few shows back then, But my cousin was the front of house sound tech for them there from 1976 thru 1988 then down at Symphony Center in Chicago,  Ravinia has a  wood dance floor stage with seating under a roofed pavilion which extends out to outdoor lawn seating with delay speakers placed all over the lawn. as i worked for them from 1976 thru 1999 while my father was the technical Director for the venue.

The following link gives the whole history of Ravinia Festival and the CSO's

history there.

https://en.wikipedia.org/wiki/Ravinia_Festival