F cabin: The A seats (1A-4A) are singles, no one on either side of you. The windows don't exactly line up with the seats in F, all I can tell you is that row 1 does not have great window views.

Y: Bulkheads 5C/5D are probably the best. There isn't much room to reorient the carts between F & Y, & 5B appears to be in the way (just guessing, I've sat in 5C, not 5B). On the left side only 5A has underseat storage ahead of it, I observed the 5B pax stashing his stuff there, lots of legroom in row 5 so maybe 5A pax didn't care.

In the exit row area, there are two exit rows but three rows extra extra legroom, seat pitches there range from (my recollection) 35-42".

The seats on these CRJ-900's provide terrible lower back support. Bring something for lumbar support or grab a blanket on your way in. We need to keep harping on this so it is addressed in future deliveries -- remember there are another 34 or so of these planes on order. In my not-particulary-humble opinion, these seats collectively (both F & Y) are the most uncomfortable in the NW fleet.