I can tell you it definitely is a holy day in orlando because I was there last year on Dec 8 and we went to mass at the Mary Queen of the Universe Shrine. Believe me, I know sometimes it is inconvenient, especially when you have to rent a taxi to go, (and especially when you have to do it twice in one week), but if you are like me, you will feel a lot better about going than you will about skipping mass. Have a great trip!