As Ben says, those who miss out will receive "a guest pass for a future visit to the expanded Toronto Signature Suite." That is actually a great way to handle this. I can't think of anyone else doing such a thing when their top-tier lounge is closed for renovations...
If it is closed , then it is not open .
Korean Air takes the cake for lounge closure gestures. When they were renovating the first class lounge they gave out a gift from Christolfe or Baccarat when checking in to the miler lounge that had just finished renovations. Built up a nice little collection of crystal champagne flutes during that time
This is a thoughtful (and relational) gesture that also encourages the customer to return to AC and is a raincheck for the missed experience. Alternatives, like a meal voucher or a gift, are well-intentioned but transactional in the moment; they don't give the customer a lasting reason to come back. I've been to the (now former) Signature Lounge in YYZ, and it is classy, yet understated, and in a good way. Can't wait to see it post-renovation.
