There's a parking lot right there, but it fills up quick, so aim for 9 am or so.
I drive through this area every couple years, and I've stayed at the Holiday Inn Express right across the road the night before, and they let us park there the next morning while we hiked. These "rocks" are like nothing you've ever seen.
To get there, you'll be driving up I-17 from Phoenix. Halfway there, take the Hwy 179 exit north, and drive about 15 miles towards Sedona. Oak Creek Village is the town with the Bell Rock Park.
Then Sedona's just north of there, and is a great place for lunch. It's a very scenic town, surrounded by the huge red rock mountains - Hippie/visionary town, lots of crafts and restaurants.
Sedona is actually worth a day or two stop. Lovely town, surrounded by hiking trails into these crazy red rock mountains. And there are dozens of restaurants. It's about 4K feet, and usually not too cold and snowy. (Flagstaff is over 7K feet, so dress accordingly.)
From Sedona, if you don't mind mountain driving, and there's not much snow, keep going north on SR 89 to Flagstaff. (It is not an easy road-- several sets of switchbacks-- and the snow can come early and hard, so you might prefer to go back to the Interstate from Sedona to get back on the road to Flagstaff.)
The Oak Creek Vista on 89A is spectacular. (Again, this is not easy driving without an SUV and experienced driver.) It's about 20 miles south of Flagstaff. IT's a really spectacular (but difficult in winter) drive.
Watch for winter weather. Phoenix will be nice and warm and sunny, but Flagstaff has super-winter weather. Snow is normal all winter long, and blizzards aren't unusual. They'll come up suddenly too, especially high in the mountains.
Prescott's another neat town-- has a beautiful town square with Wild=West=era buildings. Again, though, in the winter, this might be more hazardous driving than you want.
(Interstate 17 from Phoenix to Flagstaff is usually fine in my experience.)
Have fun! Do think about stopping in Sedona if there isn't a weather issue. That Bell Rock hike is great if you're into easy hikes (as I am .
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