Let's see...Desperately Seeking Susan...Oh, it's hard to explain. I'll post a summary from IMDB. But this is the only movie she was ever good in. She basically played herself. Rosanna Arquette was great and I loved Aidan Quinn. It's a romance. So if you like romantic comedies, this is a good one. It was a big hit when it came out if I remember correctly. She and Rosanna were great friends for about 10 minutes. Madonna's Sean Penn days.
Bored Roberta spots a regular personal ad in the paper titled 'Desperately Seeking Susan'. She passes the time following the progress of Susan who regularly contacts her boyfriend Jim through the Personals. When she sees the two are meeting in New York Roberta goes along, follows Susan who sells her coat for money in a thrift shop. Trying to emmulate Susan, Roberta ends up buying Susan's coat. Finding a locker key in the pocket she in turn advertises for a meeting with Susan. Jim sends his projectionist pal along to see what is going on, and when Roberta knocks herself out he assumes she is Susan. Then things start to get complicated.
That's a sucky plot summary, but the best I could find. Susan was around when some sort of mob guy was murdered, and now they're looking for her, Roberta sort of becomes Susan in personality. Man, it's hard to explain. Sounds strange, but it's really pretty good.
Ah, the 80's.