First time being a Bonvoy Ambassador (mainly due to all the stays for HK hotel quarantine) after one year of being Titanium last year. I would echo what everyone else has said before, and that the benefits of being an Ambassador is noticeable over Titanium, but not worth to chase it. The main differences are

- Hand written note cards acknowledging being an ambassador (at Marriott/Renaissance - a bottled water or potato chips in room: at W/Ritz Carlton - chocolates and macaroons)
- Advance upgrades to full suites at some properties (Sheraton YVR, Marriott Ottawa, Ritz Carlton Vienna and HK), advance upgrade to premium rooms (higher floor, better views, rooms with balcony or larger rooms etc) at every hotel, but zero suite upgrades even though hotel inventory has availability at Renaissance Montreal and W Toronto)
- Check in staff usually acknowledges and say thank you for being an Ambassador
- 9am check in granted with Your24 at Renaissance Montreal
- Upgrades most often also granted for second room booked under my name
- emails to Ambassador replies within 24 hours

I’m satisfied with the benefits but wish there would be more incremental benefits over Titanium like more bonus points or SNA, otherwise it’s not worth to spend $20K a year.