The choice of route for a day out but take into account the ability of the weakest member of a party. There's no harm in setting a challenging route, but there has to be a contingency plan and escape routes factored in to the planning. There's no harm in cutting a route short, or turning back. The mountains will still be there next time!
The pace should be set by the slowest member, and they should be given time for rests. It's better to walk at their pace, than to find yourself hanging around for them, and much more social!