My longest train trip was from Old Saybrook, Conn., to Portland, Oreg., in 1994 . At that time there were two possible routes, and I used one in each direction:
Westbound: Northeast regional (the trains still had individual names then, but I don't remember this one) to Philadelphia (connection was too close at New York but feasible at Philadelphia), Broadway Limited to Chicago, California Zephyr to Denver, and Pioneer to Portland.
Eastbound: Empire Builder to Chicago (a section running from Portland joined the main section from Seattle at Spokane), Lake Shore Limited to Boston Back Bay (connection at South Station was too close), Northeast regional to Old Saybrook.