We managed to get tickets for Grey Gardens at the TKTS the week after the Tonys (which was no easy task, unless you wanted partial-view) Anyhoo, the seats we ended up with were Row J in the Mezzanine (the last row) and they were still good seats. The Walter Kerr is a small theatre and I can't imagine any seat being bad.
I hope you enjoy the show and whichever seats you pick!
"A bird doesn't sing because it has an answer, it sings because it has a song." -- Maya Angelou