At the end of our trip to Switzerland we will either be spending three days in Lausanne or split the time between Lausanne and Geneva (2 days in Lausanne and 1 day in Geneva). I am traveling with my parents and two younger children (6 and 3). We were originally thinking of staying in Geneva the night before we go back home to make traveling to the Geneva Airport easier with kids. I don't know if we want to travel 40-60 min. from Lausanne to the Geneva airport before a VERY long flight back to America. What are your thoughts on this? Is two days in Lausanne enough? Would it be way more convenient to stay in a Geneva hotel the night before departure? It is sometimes so hard to plan a trip with children, especially to a place we have never traveled before.
Unless your flight from Geneva is quite early, I would travel on the day from Lausanne. The disruption of a 45min train to the airport as opposed to 10mins is not worth the effort changing hotels.
I would stay in Lausanne unless your flight leaves really early. Staying in Geneva won't save much time on flight day. And staying in Geneva on that last night means you will have yet another hotel change to deal with, and all the packing and unpacking that requires. On the other hand, kids are a wildcard!
I do this trip every few weeks and I've done it with children. If you have a morning flight and you have the option, stay in Geneva in a hotel that has an airport shuttle. If you are flying the weekend rather than during the week and have a morning flight, stay in Geneva at a hotel with an airport shuttle. If you are flying after 11:00am and during the week, then it would be up to you if you opt for Lausanne or Geneva as you'll have a bit more time and it will not be as busy. I can recommend the Movenpick hotel in Geneva. I had a flight cancelled by my airline and they placed me there for the night. The hotel was great and it was very convenient to take their airport shuttle in the morning. If you flew into Geneva, you know that the trains do go directly to the airport, but with children, it's always nice to have it be a bit easier.
EDIT: I just noticed that your earlier post indicated that your flight departs at 2pm. In that case, I would opt to stay in Lausanne or Vevey as I commented earlier. Early morning flights are never easy with children, but you'll have plenty of time to get there and catch your flight and you can enjoy your last day without a change.