Can anyone recommend a reputable, affordable day tour to Paris that uses the Eurostar? Thank you for the YHA recommendation!
We did a one day Golden Tour from London to Paris on the Eurostar. Very happy. Mind you it was pretty fast paced.
We created our own 2 day trip from London to Paris via the Eurostar. We left London early in the morning but, due to the time zone change, it was nearing Noon when we arrived. We stayed completely busy, so I would suggest that you consider at least 2 days in Paris.
With a good guide book and map, I think you can do it on your own without a tour. The metro is really easy to navigate and not expensive. In one day back in November, I got into Paris around 11 am, immediately went to Notre Dame... stopped for lunch, then made it over to the Eiffel Tower and went up at dusk. I could have gone home in one whirlwind day, but I stayed overnight to go to the Louvre the next day.
If you leave London really early in the morning, let's say 6:30 (the first train leaves at about 5:00 am) you'd be at the Gare du Nord at 9:45 Paris time. The hop-on/hop-off bus has a stop right in front of the station. You could do a good 2 hour bus tour and still have time to look around a bit before finding a place to have a good lunch. After that you could shop at one of the avenue Haussman department stores or go to a museum or the Eiffel Tower. Have a nice dinner later and take a late train back to London where you get back that hour you lost when you got to France.