The Modernist architect Frank Lloyd Wright wasn’t a hoarder. But he did save just about everything — whether a doodle on a Plaza Hotel cocktail napkin of an imagined city on Ellis Island, his earliest pencil sketch of the spiraling Guggenheim Museum or a model of Broadacre City, his utopian metropolis. Since Wright’s death in 1959 those relics have been locked in storage at his former headquarters — Taliesin, in Spring Green, Wis., and Taliesin West, in Scottsdale, Ariz.