I liked the one at night so you could see the lights, also. I've taken one in the day time, also, just for something to do for a change. I'm not picky, they all seem fine to me, I don't expect anything but a boat ride. I did take the one at night on a smaller boat and had a good seat to see the lights, I think that is best, of course (I used Bateaux Parisiens at night).

go to www.sunrisesunset.com to find out those times by city and month of year.

Thank ya'll for the replies. We'll be in Paris the first week of July. We'll just do the cruise tour and just have dinner somewhere.