I'm very curious to see button ante in action - I get the concept (it's pretty simple) but I haven't played a tournament with it yet.
Places to stay - there is an "always-on" deal with a pretty nice hotel downtown called Hotel Vogue: check there for details -
https://www.playgroundpoker.ca/hotels.
Many people lately have been using AirBnB to find a good place, usually with friends.
Beyond that, there are a ton of good hotels at every price point in central Montreal.
When people haven't been to Playground before they tend to think the whole accommodation thing is going to be a huge pain, but we have a ton of repeat visitors and have done plenty of big events in the past and... it just works. At least I never hear wide complaints or problems.