Young readers, mystery fiction, Girl and Dog, Eccentric Family in Hotel, Treasure hunters arrive, pirates

Looking for a young readers' book, fiction, about a girl and her dog who live with her eccentric family, possibly a grandfather too, in a rundown hotel. Treasure hunters show up in town looking for a hidden treasure somewhere in town. The novel may be from the 1980s or early 1990s.

The Pink Motel by Carol Ryrie Brink?

>2 MissSquish: The story definitely did not take place in Florida, but it seems like a similar plot.