Gray Butte makes a great acclimatization hike before hitting Mount Shasta, especially if you are coming straight in from sea level after a long drive. The views of Shasta from it's summit are probably even more stunning than the views of the surrounding countryside from the summit of Shasta itself, making it well worth the relatively easy effort required. A strong mountaineer should be able to make the summit in about an hour, and the trail is easy enough to make a nice family outing as well.
There is a straightforward 1.7-mile trail from Panther Meadows to the summit. The first .2 miles pass through the meadows, with nice views over flower fields to Mount Shasta. Just over a half-mile or so through gentle forest you come to a junction along a ridge. Turn right and follow the trail as the summit of Gray Butte briefly comes into view. Dipping down to a saddle, the trail traverses along the far side of the peak seemingly forever. Once you are absolutely sure you have gone too far, the trail turns back and quickly gains the summit. You could probably scramble the rocks from that saddle and save yourself a lot of time. either way you get there, majestic Mount Shasta dominates the view from the summit.
Follow instructions to Mount Shasta. Following the Everitt Memorial Highway, the trailhead for Panther Meadows and Gray Butte is two and a half miles beyond Bunny Flats on the right. The road is gated at Bunny Flats every winter until it melts out the next year, which may not be until early July depending on snow conditions that season.
There are no entry fees required for the Mount Shasta Wilderness, beyond the requisite forest pass for parking. The meadow is a fragile area so stay on the trail at least until you hit the forest.
There is a primitive dusty campground at Panther Meadows. There are plenty of other places to camp in the area, most with no fee required.
The Mt. Shasta Ranger station can provide up-to-date info on conditions and other helpful information: (530) 926-4511