Much of my backpacking activity over the past 40 years has been in the Grand Canyon (so if anyone has a question about hiking there, I'll try to answer it) on trips ranging from 5-10 days over most of the named trails and a lot of different routes into places few people go.  After reaching the Rim and getting cleaned up (usually at one of the lodges where we've booked a room, but sometimes just at the campground showers), the first post-ascent meal will be at the El Tovar Dining Room on the South Rim, or the North Rim Lodge Dining Room when there during their much-shorter season (May-Oct).  Both are excellent, but you'll need to make a reservation in advance as short-notice availability or cancellations are extremely rare during most any season for either.

If you do eat at El Tovar, be sure to get a bowl of the shrimp bisque as an appetizer if that's one of the daily specials -- it's the best I've ever had, and that includes a lot of tasting in New Orleans and other places where it's more of a regular item on the menu of mid- to higher-end restaurants.