Probably the most famous whimsical Gothic would be Jane Austen's Northanger Abbey. I have not run into another romance like it. However, I recently read a Regency Romance titled A Very Unusual Governess by Sylvia Andrew which tries to add a little supernatural element to it. Regency romances in general have a levity to them, so the supernatural element could make this a whimsical Gothic. I would recommend the book to anyone who would like to read a lighter Gothic. If anyone knows of any others, I'd appreciate the suggestion.

What is a whimsical Gothic?

I've heard good things about Jane Austen's work.