I think most Seam users are not only using lighter architectures than what you are used to with J2EE but also a lighter (more agile, though I hate that term) process. So, I doubt you'll get many responses back from people using heavy
design processes with Seam.
If you ask specific architectural questions, I'm quite sure you'll get some interesting responses.
Most of those diagrams that show lots of little blocks with words like DAO, servlets, etc. say very little to someone outside of your working group because they assume we share a common vocabulary and belief system about the constituents of an application written in Java. Even worse are those humongous class diagrams generated by some UML reverse-engineering tool. I think Fowler's UML As Sketch blog does a good job of stating an excellent way to use UML (http://www.martinfowler.com/bliki/UmlAsSketch.html) - mainly as a sketch tool for discussing specific aspects (e.g. a component) of a system of interest.