This also holds true on the 737 as well. The trips between the 320 and 737 vary more by base than fleet type. Based in LAX on either fleet will have more all night flying, where based in DEN or IAH it’s fairly easy to avoid. Pairing construction is about the same within the same base from what I’ve found. The biggest difference between the two is that the 320 is a much more comfortable cockpit, where the 737 is a much larger fleet with more bidding options and potential growth/advancement.