Personally I would stay in one of the cities, instead of rushing through both. But if you must you can use the following to help you plan:
Rick Steve's Rome itinerary, between 2 to 7 days https://www.ricksteves.com/europe/italy/rome-itinerary
Rick Steve's Paris itinerary, between 2 to 7 days https://www.ricksteves.com/watch-read-listen/read/articles/paris-itinerary
These itineraries will help you prioritize the sights you want see.
