Pretty much what @armoured said was our experience at the border, if not even easier. In our case we decided to play it extra safe and have a return ticket, but we ended up not needing it. We bought it on the same day we traveled so we could catch the 24h full refund window. Purpose of visit: tourism, staying where: toronto at friend's house, staying how long: 4 weeks, and that was it. Spouse had an ETA.