B.C.
500 miles is a long trip to do in on day. I've done longer, but 500 miles is a long trip.
I would look up the web site for Dines, Drive-ins and Dives. Then find any of those restaurants that are along your route. Stop in there for lunch or dinner. I've eaten at several of the restaurants they've reviewed and they have always been excellent. AND they are never one of your typical restaurants. It will be a nice surprise.
If it were me I would want my wife to surprise me by celebrating father's day the weekend before. I don't know how you do father's day, but for Mother's Day, my wife said she wanted "Orange Chicken" and to spend some time with our kids. Orange Chicken is one of the few things I've never tried to cook. So I took her out to eat Friday night for Orange Chicken. Saturday we went to IHOP for breakfast. Saturday evening we went on a horse and carriage ride with two of our kids and their spouses. Then I took all of us out to dinner and out for dessert. Sunday we went to one of kids homes for dinner.
We made a weekend of it for Mothers' day. I would recommend you do something like that for him or Father's Day. Make a weekend of it. One Father's day we went sailplaning. The instructor flew it most of the time, but I got to fly it a little. One time we went for a walk along the beach and a picnic lunch. We took our suits and went swimming. We have been to Medieval Times, Knott's Berry Farm ,Disneyland, Sea World, and took a gondola ride Newport Harbor. Look to see what Groupon has to offer or any one of those type of sites. And have fun.
Good luck to you and yours.