Congrats! I retired early three years ago...I can't recall what I wore on my last day though the Stones song 'I'm Free' was in rotation several times. I'd say wear what makes you feel happiest.
Best wishes to you...
Something classic and rather understated like Eau Sauvage EDT if the retirement occasion takes place at the office/in the work environment. Something still classic but slightly more formal and higher projection like Boucheron PH in EDP concentration, a concentrated flanker pour Pour Monsieur etc. if the retirement is also marked with dining, going out, evening/after hours socializing etc.
This one is easy. Lord willing in 10 years I’ll wear Creed GIT for the last day at work. Closest thing to a signature scent that I’ve had in my career. I hope to retire at 64, and my wife at 60 that same year.