There is a cluster of hotels in the Cordelia Junction section of Fairfield from which to choose, each at a different price point, and most of them provide breakfast. The reunion headquarters will be centered at the Homewood/Staybridge suites area, but you can stay at any hotel.
Homewood Suites Fairfield-Napa Valley (northwest side of I-80)
Staybridge Suites Fairfield Napa Valley (northwest side of I-80)
Best Western Cordelia Inn (southeast side of I-80)
Comfort Inn Cordelia (southeast side of I-80)
La Quinta Inn Fairfield Napa Valley (southeast side of I-80)
Travelodge Fairfield Napa Valley (southeast side of I-80)
Motel 6 Napa Valley (southeast side of I-80, no breakfast)