Donna - off the top of my head:

Younger kids expect structured activities. Choose a destination where that's available to them and ideally offer supervision so their parents can have a few hours to themselves. Ski school group classes for kids is an excellent example.

We find multigenerational travel only works periodically. Grandkids aged between 3-6 make it easiest for a trip, as school schedules do not impact on vacation availability. Smaller kids, school aged kids active in sports and parents who are switching jobs or at the point in their career where they need to put in extra time are not conducive to multigenerational travel.

Some trips are best with one child and their family rather than finding a vacation destination that suits all children and their families. For example, one loves the beach and dislikes cold weather. Skiing or winter sports are not ideal for this child to participate.

If it's a four generation trip, gauge the oldest person's energy level and think through physical restrictions, if any. They may well want to go, but find they cannot keep up with the younger group once they are there. Their diet may require special meals rather than dining out.

Identify diverse interests to provide something for everyone. Most, but not all, of us downhill ski. We gear a ski destination towards a town with other winter activities for the non-skiers, rather than the best location for downhill skiing.

Reservations - ask about family friendly restaurants and book ahead. Size the number and kind of rental cars needed, consistent with the accommodation arrangements.

People are flying in? Expect delays or other problems. If the accommodations are far from the airport, what's the back-up plan for lost or delayed luggage?

Accommodations - generally easier if there are kitchen facilities so some meals can be eaten without leaving the premises. Going out for a group breakfast can be a real headache if not everyone gets up around the same time.

Extras - agree on who will pay for what.

Lodging for everyone under one roof or not? If that's a requirement, start looking early for best selection.

Expect some in the party may have schedule restrictions. If that's the case, keep it comfortable for those who can make part, but not all, of the vacation time. For example, a weeklong golf school doesn't work well if one or more can only come for a long weekend.

Cheers, Anne