How old you look and act may also play into it. While most hotels will check id, they're principally looking for name, not DOB. If you look a little older, I doubt you'd have any problem.

Against that, the downside could be a pain in the neck, particularly if the city is full. Having the manager's name in the reservation record - and you noting the manager's name as well - will be a good idea.

If the hotel is on the ball, they will clean out the booze portion of the minibar in your room.

You might want to book with a fspp agent for the amenities as well. Plus, if things got sticky at checkin about age (ie: front office manager says, "he/she shouldn't have told you 18 was ok), having a fspp agent in your booking as well won't be a bad fact.

Have a great trip.