First, before I answer note that this is just my opinion and it's mainly about models.
The way I see it, areas can be just so evil.. If you have many areas your solution explorer becomes a maze, and it can get so hard to find something.
I suggest creating a new library project inside your solution, and put the logic in there.
The best benefit (and it's not that you can find what you're looking for much easier) is that your application becomes much more modular. If you create a library and specify a reference for it in your ASP.NET MVC application, you can't easily make a mistake and involve UI in the logic.
