Silverlight shouldnt affect much, since the underlying datastructures are gonna be similar regardlness of language/technology.
I ended up going with a 'Hex' structure which is basically the tile..it stores reference to unit on it, as well as reference to a polygon object (which is what renders to screen).
The Unit structure stores reference to the hex it is on as well as the player it belongs to.
I did not think of 'civilization' or races but thanks for suggesting that. I will need to factor that into my design as well somehow but the thought eluded me until now.
I guess experimentation is the key