Most hotels require you to be 21 to get a room. Some 25.
Maybe a motel 6 may let you be 18.
Call and ask.
Also, you have to have enough for the damage deposit.
At most hotels this is usually about 1 to 3 nights worth of stay.
If you have this, call and ask the hotel how much they require.
Don't forget all the taxes a hotel charges. It can add 20% to the bill.