Didn't do that on the tour - but the train in to the city from the DLP station takes about an hour each way. I did Paris on my own without an issue. Some days just completely by myself and others I took the train in and met a tour group there. I noticed a number require you to meet them in Paris anyway - so I would find a tour that you would all like and meet that (or 2 shorter half day tours). I had good luck with City Wonders tours - I used their Eiffel and Seine tour as well as the Loire Valley tour. I also used a number of the Rick Steve's recorded tours for the Latin Quarter, Notre Dame, etc. but that wouldn't work well with kids. If you have a very early start time I would splurge on a car into the city vs. the train.