OP, HoJo's web site says, "You must be at least 18 years of age in order to make reservations." It also states that a valid credit card in the same name must be shown at check-in. This is an option if one of the 18 year olds in your group has a credit card. You don't have to use the card to pay for the room, but they require it in case you skip town before paying (not saying "YOU," just someone in general

).
You might want to look at this list:
Good Neighbor Hotels.
I just called Candy Cane Inn for you (just picked one from the list at random). I gave the following scenario (which I think is not exactly your situation, but more extreme): 7 girls, 1 18 year old, 6 17 year olds Can they rent a room?
The answer: The 18 year old would have to rent the room for everyone. The 18 year old would need to have a credit card in her name. There is not one room that sleeps 7 so 2 rooms would be required, but one 18 year old could rent both rooms as long as the reservations are linked and the credit card could hold the charges of both rooms.
Hope this helps get you on the right path.
In the US at 18y ears can buy anything including a hotel room, just not liqour....
This is not correct. Trying renting a car at 18 from any major, reputable company. Hotels have restrictions as well. (And by point of clarification, you are not buying these things, you are utilizing them for a brief period.)
- Dreams