Vista - Simple Map Control

I have just started using Avalon. I am developing a map control for
displaying simplistic jpeg representations of floor plans with the ability to
add graphical items that can be interacted with remotely from our software
application. The items need to show state, receive selection focus and be
clickable.

It seems that there are a number of ways of doing this:

CustomControl
UserControl
Templated Content Control

Can someone give me some advise on the best accepted way of doing this?

Thanks