looking at the 1996 OAG International Edition on departedflights.com, and acknowledging that it’s only a portion of the entire volume, I find the following Boeing aircraft types:
727-100
727-200
737-200
737-300
737-400
737-500
747-100/200
747-100/200 Combi
747-300
747-300 Combi
747-400
757-200
767-200
767-300
777-200

it might be an interesting exercise to piece together an itinerary using these 15 types and keeping repetition to a minimum