In boom times, Sumner Regional Health Systems went on a buying and building spree, snapping up properties, including land near its flagship hospital here, with plans to keep expanding. Now, as part of restructuring to shore up its finances, the organization hopes to sell 20 pieces of property, including medical office buildings and vacant land with an estimated value of over $14 million. Meanwhile, the health system's top officials and a group of consultants they retained earlier this year disclosed that they're evaluating unsolicited offers from "interested parties" covering a wide range of other strategic alternatives, although no action is imminent.