Hi Greetz,

I would suggest Vue, which is the reference in term of software for landscape modelisation. There is an architectural bundle that might actually be interesting for you:
You can check the following address:
http://www.e-onsoftware.com/products/vue/vue_archi/complete/

However, if the render quality is not so important for you and you want instant results, lumion is a solution.

Hope this helps.