Ok I just gotta ask this.  When setting up a new website project, do you.... 

1. Use App_Code folder to store you data layer class files and use your code behind pages to touch your data layer?  or....
2. Setup a UI project which your code behind pages call and your UI project calls your Data layer (separate project again)?

The 2nd way seems a bit overkill.  Mostly what the UI project does is just call the Data project so it seems like an extra hit to me.  What is the value, if there is any? 

 And for items on the aspx page, do you use your UI Project and pass it a drop down list from the code behind and let the UI fill the drop down list?  Again, what is the value if any?  It seems like overkill again.

 Thanks in advance!

I use this solution structure:

• Library
• BusinessObject.Library
• Utility.Library
• WebControls.Library
• WindowsControls.Library
• Application
• WebApp
• WindowsApp

 By putting my business objects, utility objects, and ui objects in their own libraries, I can create multiple web and/or windows apps that reuse those components in a mix-and-match style.

My business object library includes the data access layer components, but that's just because I'm not worried (at the moment) about needing to support more than one database vendor's product.  If I were, I would have separate data access libraries.