But potential visitors are advised to book now for next year.

But visitors eager to recognize special service are advised to add up to 10 percent of a bill.

"We can help advise visitors on how to get tickets," he said.

In fact, first-time visitors might be well advised to go with a tour group, and only for a short stay.

Since conditions can change quickly, visitors are advised to get up-to-date information before going.

This can take a few hours and such visitors are advised to be patient until clearance is given.

Specific activities may be booked for private events, so visitors are advised to call in advance.

Since many stores have extended hours, prospective visitors are advised to call ahead.

Bison may be dangerous and visitors are advised to view them from a distance.

Yet the sun is often so intense that visitors are well advised to bring sunscreen.