I grew up watching that one. Agree re: Douglas being comically unsuited to the role. But the bus to Cartagena moment is gold! Something about this film is very endearing despite its general silliness. Curiously, having seen it 10+ times at least, I never felt it was an Indiana Jones ripoff just because Joan isn’t really interested in any of that stuff except when it comes to her sister - and she is the protagonist.
Personally, I LOVED Romancing the Stone...perfect blend of action and romance featuring my favorite Kathleen Turner performance. I love the transition that the Joan Wilder character goes through in this movie...from prudish, uptight writer to passionate woman ready to live the lives of the heroines she writes about. I think Turner's performance in this film deserved an Oscar nomination more than Peggy Sue Got Married, which did earn Turner her only nomination. Didn't really care for Jewel of the Nile though.