re: London to Paris 1 day trip… ???

My stepdaughters went on an organized day trip to Paris that included train tickets, lunch at the Eiffel Tower, bus around to major sights, etc. They did see a lot and there was some free time built in. It was an exhausting day but they did feel like it was worth it.

The thing about trying that on your own, at least for me (and I love organizing my own itinerary), is that it takes me a bit to get my bearings in new places no matter how well I seem to plan. So I waste valuable time navigating. You might be more successful.