I am planning a trip to France and Switzerland for myself and my beau. I am trying to come up with a coherent itinerary and am having some difficulty. We have 12 days total including travel days. I would like to visit Paris and he would like to explore the Bernese Oberland region of Switzerland (specifically Lauterbrunnen, Gimmelwald, Murren, Wengen etc.) I may add that we would also like to keep open the option of going back to Venice (2 days or so) for this year's Biennale.
This comes on the heels of a 22 day whirlwind of Italy last September/October (Venice, Florence, Cinque Terre, Siena, Assisi, Sorrento, Positano, Capri, and Rome). Any and all advice would be well-appreciated.
Your problem is very simple: 12 days including travel means 10 days on the ground. Since you have to get between places, there's just no easy way to do justice to Paris, the Berner Oberland, and Venice in 10 days (that's only 3 full days in one, and 2 full days in the others, once you subtract travel days between them). If you don't mind 2-3 days in each destination and lots of time getting between them, you can do this; otherwise, you can't. One complication is that getting to and from the Berner Oberland takes time. A cursory look on the Bahn website shows that Paris to Interlaken at the shortest is 6:03 with 2 changes, and Interlaken to Venice at the shortest is 6:40 with 2 changes. Then, of course, you have to get from Interlaken to Lauterbrunnen, and then up into the mountains (and reverse the process when leaving for Venice). So, you basically use most of a day each time. In your situation, I'd pick two of the three, and see them with less moving around and train shifting. But that's me; you may not mind a "tasting platter" and lots of trains.
Your beau (and perhaps you) would probably want at least 3 nights in the BO to allow for 2 full days there. That means if it rains or fogs over there's a good chance of one nice day; 4 nights (3 days) would be more certain. You can see more if you do not squeeze Venice into these 10 days, but you can squeeze it. On the other hand several very interesting, if perhaps not quite so iconic, stopovers lie between Paris and Gimmelwad.