Vancouver Marriot: Can my parents book a hotel room for my friend and me for my 19th birthday? ?

Last time I was at a Marriot, no unaccompanied minors under 20.

Marriott often lets those 18 and older check in, but they say that you have to check with each hotel. I guess they don't want to make the data that public for some reason. 

As others have said though, generally the person that the room is booked under will need to be in person to check in. I've even had problems at a Marriott when my wife made a reservation for me under he name even though she wasn't checking in.

In the end, each hotel (even under the same brand name) will have different rules or at least different enforcement of the rules, so you should call the hotel directly.

Are you checking in on your birthday or later?  Because even if you check in 1 day before your birthday you are legally under 19.

Did you parents book the hotel in your name?  Normally check in procedure is to ask for your identification and credit card it was book on.  So it will definitely be easier if your parents check you in.   Unless you have your own credit card to switch it to, and not a gift card type, the hotels hate those.  hotels will typically precharge the $200 or more over the total hotel bill as a damage deposit.  So you can call and ask if they take cash and bring that much cash ($200 plus total for stay)

Get your parents to call or email the hotel and ask what their policy is. I could tell you what I think, and I could be wrong. I don't work at the Vancouver Marriott.

ask your parents                   

They can book it, they have to check in, then you take the room. Then, when you trash it, your parents get the bill for $10,000.

Marriott doesn't have a standard age across all properties.  Call them and ask.