I have 3500 recent PIC in the 319-321. There is some stuff I don't like, but after going "back" to the NG737, the scarebus is a dream. The 800 (320) equivalent lands at speeds that are more normal for the 321. The 900 is so tail strike happy they increased the approach speeds massively (above 150 lots of times), to reduce the pitch attitude on landing.
Flaps 3 or full on the bus? Use your best judgement first, and company SOP second. Then thank bejesus you aren't flying a super guppy.
BTW I like all Boeings better than a 320, but the 737. P.O. S.