By the end of the ten-year program the planning teams, east and west, had turned out an impressive volume of carefully and imaginatively conceived plans, not all of them for park museums. Within the first year management saw the value of dovetailing wayside interpretation with museum content, so the Museum Branch assigned planning for both to the teams. Thus Sutton and Bierly devised the exhibits not only for the new visitor center at Flamingo in Everglades National Park but for the series of interpretive stops Superintendent Daniel B. Beard had proposed along the road leading to it. Management could not resist using the teams' skills to plan temporary exhibitions such as those for a governors' conference, a World Forestry Congress, and a Boy Scout Jamboree in 1960. Team planners were lent to Mississippi, North Carolina, and the Army to aid in museum development projects. Bierly's broad talents led UNESCO to borrow him as an expert to assist the Rhodesian government in planning and developing its museums. Spangle interrupted his regular work with the western teams for a three-month park planning assignment in Jordan and later served on the team sent back to Jordan and Turkey.

The history team had a share of these extra duties and carried another burden. Because the Civil War Centennial fell within the Mission 66 period and the Park Service had most of the war's major battlefields, the team faced the need to plan exhibits for a daunting succession of battlefield museums. Similarity in the material culture and in the general nature of story content taxed the ingenuity of both curator and designer to make each of these museums unique and specific to its place yet clearly related to the others. Watching visitors use the museum accompanying the Gettysburg cyclorama left little doubt that the history team served the centennial well. For some of the later projects the eastern team shared this load and demonstrated its capability in planning Civil War exhibits.

The sheer number of exhibit plans the three teams produced made their adequate review a problem in itself. To ensure that they merited approval, Ronald Lee instituted a multidisciplinary scrutiny of each. Beginning in February 1957 he brought to the Museum Branch as often as necessary a delegation of interpretive and subject matter experts from the History and Natural History branches. A Museum Branch representative explained each proposal in detail, after which open discussion led either to agreement or a call for revision. When Lee became satisfied as to the accuracy, feasibility, and likely effectiveness of the exhibits proposed, he defended them at the director's plan review. During the first five months of this procedure twenty exhibit plans along with thirty museum prospectuses passed such careful screening.

Good museums depended as much as ever on cooperation between museum specialists and architects. The visitor center concept involved enough fresh problems to make close collaboration even more important. Fully appreciating this, Lee was instrumental in scheduling two conferences among Service interpreters, museum specialists, and architects early in the program. The first met at the Eastern Office of Design and Construction, Philadelphia, for a week in November 1957. The conferees discussed visitor centers currently on the drawing boards, debating details and general concepts. A similar meeting at the Western Office of Design and Construction, San Francisco, followed in February 1958. The combined report clarified thinking on visitor center functions and design factors. Lee and Chief Architect Dick Sutton submitted it promptly to Director Wirth with a list of recommendations.

One of these addressed the principal point of contention at the time between architects and curators. The architects pleaded the merits of open design. While this trend influenced plans for many types of structures, it seemed especially important that visitors entering one of the new park centers not lose contact with the outdoors. Curators heartily approved of openness for lobbies and many other interior spaces, but they stressed the need for control of light in rooms containing museum specimens. Lee and Sutton agreed on this, and most Mission 66 visitor centers followed suit. Some architects continued to oppose the judgment that concern for specimen conservation should outweigh the visual attractiveness of windowwalled museums, however. They dubbed exhibit rooms that met museum lighting standards "black boxes" and later found allies in the exhibit design field.

During 1956 the Museum Branch continued to add artists and craftsmen to its laboratory staff to fill specific needs. John Babyak, a former preparator at the American Museum of Natural History who possessed useful experience as a rigger, reported in April. Marion B. Stewart joined the staff as an artist in June and worked principally on preparation. In June also the laboratory hired Alfred Lloyd Lillie, a young sculptor fresh from art school whose talent far exceeded the paper qualifications that determined his pay. He served well for nearly a year before undertaking advanced studies. Later he fulfilled special sculpturing assignments under a "when actually employed" appointment and returned to full-time status for a while before joining the Boston University art faculty.