I'd say the drive would be between 2 - 3 hours. What were you looking to do out there? The park is absolutely beautiful, but rustic. They do not sell water or food in the park, so make sure to bring your own in. There are several short hikes that you could do within the day, depending on your hiking level. My husband and I rock climb out there and take out all our rock climbing gear, so if you have that, bring it! It is a rock climbing mecca. Crossroads Cafe is a great place to grab a meal.
Depending on what time of the year you are going, it may be extremely warm. We don't usually go camping there after May, because it is over 100 during the day.