I cant answer your specific question, but in terms of architecture in general,
I really found using reference applications very helpful.
In particular is the CommunityForums source code from telligent systems.
Its a really solid application that actually works really well, is well programmed
and is pretty - something that most other reference applications are missing.
Also the Windows Forms reference application from Infragistics to show off
their controls was really good, especially given the ebook that you can download
discussing the architecture.
Then you've got the reference applications at
www.asp.net. - Bear in mind
that the logic layers from asp.net applications are often very similar to
those of Windows Forms applications. The same is true of the data access
layer in most cases.
The other general piece of advice I would give is to not try and make the
perfect design. I remember spending ages trying to find where I could use
inheritance and in all actuallity there are relatively few places where it
should be used. There are often better ways of approaching a problem than
inheritance anyway.
I really would recommend looking at the Community Forums application though.
If you leave the UI project to one side you really should be able to get
some ideas that you like.
The reason I say "that you like" is because really thats what it comes down
to. I looked at just about every reference application in the hope that I
would find "The" architecture - the fact of the matter is, there is no one
application that comes close to getting it all perfect - but then again thats
just my opinion. Just don't make my mistake and think that you can't mix
and match approaches from different applications and samples.
Thanks
Simo