There is no walk-in reservation access this year for YNP camping. One must have advance reservations.
Canyon has intermittent & spotty cell connection. Canyon, like Old Faithful, is a prime location within the park and has amenities like showers (not during Covid) & access to a well operated cafeteria and visitor center.
If you are tenting, try to avoid loop A for certain--- and possible loop B.
For RV people you must reserve in advance the length of vehicle you are pulling.
For tent people, it is best to reserve a "large tent" space even if you do not have a large size tent. You will achieve a more versatile site.
Many sites are not level, but if you arrive early in the day the campground office personnel will work with you to achieve a better site if possible.
Most large tent sites will stand 2 tents. Reserve accordingly if you have 2 cars…and the length of your cars. They need details. Bathrooms are serviced often and are in good condition.
wifi hint: At Canyon campground the best wifi is located at the nearby gas station parking lot.