Organizing a group trip

Hi All – I am organizing a group trip to Japan that will take place in 2 years. Before I get started with resources and itineraries and all that… has anyone taken a group this size? I would love to hear about the logistical issues that you encountered with a group that size, and recommendations for managing them. Additional question – would you find it worthwhile to hire a guide for some legs of the trip to assist with transportation, sightseeing, and knowing which spaces would accommodate a larger group?

Thanks!

ETA: The group is 7 people, apparently I did not drink my coffee yet today and can't proofread. :/

by mekissab