If I were to rank Rush's discography, Power Windows would be very high on my list. Probably too high for a lot of folks. I really love that album. "Emotion Detector" is one of the best songs they ever wrote and Lifeson's solo is simply majestic. Right to the heart of the matter indeed.
Good call on "Open Secrets". Forgot about that one. I find a lot of their stuff from this era very relaxing in a way. Even the up-tempo songs have a nice "chill out" factor too them.
One of the reasons I've never though of Snakes and Arrows, and really Rush in general as "jam bandy" if that's the term we're going to keep using, is (and this might sound contradictory) despite their musical adventuress, I never thought of them as a very improvisational. Now obviously I've never been in a room with them writing so I could very well be talking out of my ass but knowing how meticulous all three guys are I've always assumed that they're songwriting process was just as thorough. They're certainty one of the most "composed" bands, if that makes any sense.