It depends on how long you plan to stay and if you plan to return in a short period of time. You can pick up a seven day admission pass which is $35 per vehicle and this allows you a week with unlimited entries. However, it’s great value if you plan to come back frequently or visit other National Parks to pick up an “America The Beautiful” pass, which allows you a year’s worth of access to every National Park in the United States for only $80.