Depends on when y'all are gonna be there. If it will be during a crowded part of the year, and you want to avoid standing in long lines at counter service spots, yes, you need to make reservations for lunch. Or make very good plans ahead of time as to which counter service places you want to use, and arrive at other than normal lunch time.
And if you will be using counter service spots, you might want to consider the number of tables at each location. Some have ample room with plenty of tables, and some do not.
Enjoy.