You'll want section 115 to be directly behind the Monarchs' bench, 117 and 118 are in the corner to the right of the visiting bench.
And of all the WNBA arenas I've been to - Rose Garden (back in the Fire days), Staples, America West, Target Center, Arco and the Key - believe me when I say Arco is the worst - seating, lighting, overall condition. The Rose Garden has the best scoreboards, Staples has the worst. The Key has the best seating angle (meaning even in the higher rows, you have a better view) while Staples has the best concourse. The Key has the best lighting while America West has the worst. But overall, I'm sorry but Arco doesn't match up. After watching both NBA and WNBA games on tv for years, I was, as you say, utterly unimpressed.