Where would be a good spot in the Alps for a one night stop . Will be taking the train, will not have a lot of time in Switzerland but would like to see at least a bit of Alpine vistas.

As you travel by train, you don't have a lot of opportunities. A good train connection only leaves you the choice between big cities halfway between Rome and Paris.
Presuming you go from Rome to Paris
1. Geneva.
Some Alpine vistas in Wallis kanton, Geneva lake, wonderful train route.
A logical connection.
Maybe the Rome-Geneva part is a bit too long in comparaison with the Geneva-Paris part.
2. Ventimiglia.
Coastal town on the Italian-French border.
Not exactly the typical Alps-vista but very beautiful region of the Alpes Maritimes.
Also about halfway both cities.
3. Milano
No Alps vistas
4. Turin
The Alps are in the background of Turin. Very beautiful site in winter with snowy mountaintops and a clear sky. Can't guarantee anything in summer.
5. Zurich.
Not the most direct route...
Travelling through the Alps, so OK for the vistas.

Ventimiglia or Geneva... I would suggest.

I disagree with baldrick completely..the key to seeing alpine vistas on a trip between Rome and Paris lies in WHAT YOU DO IN MILAN...change there for the TGV or other services which skirt the alps entirely through Turin and Modane and on to Paris (the typical fast route)...OR...change in Milan for a routing through Brig and Geneva and then on to Paris....or you can change in Milan for Berne or Zurich or Lausanne....lots of possibilities.