My son , age 11 mostly wore docker type pants and a collared shirt to dinner. Howerer, my friend said her son wore shorts sometimes with no problem. Remember it can be uncomfortably cool in the dining room. I think any pair of tan or black or white pants would do. Don't make yourself crazy. Do what you think is best. I don't have time in my life to worry about what a stranger's child wears to dinner. Relax and have a great vacation.