Please see my comment to the question. I strongly believe that
the project should not be driven by design patterns, but your project should drive the choice of design patterns. Sorry if this advice is not specific enough, but it is no less specific than your description of the goals of your product you need to develop.
[EDIT]
Please see solution 1: this is a good idea: "don't try to solve everything with patterns". Why? Because otherwise you can put yourself in a
Procrustean bed:
http://en.wikipedia.org/wiki/Procrustes#Contemporary_usage[
^].
—SA