Can anyone recommend a good "hop-on / hop-off" sightseeing tour of main attractions in paris (for family group some of whom would not be up to frequent metro trips).?

is it necessary / recommended to book in advance?

Separately, do the river seine cruises operate during the day, and are they worthwhile, if not at night?

John - The Hop-on Hop-off buses are called Les Cars Rouges. The tour route lasts approx. 2.15 hrs. The commentaries are in French & English with some tours equally commentated in Spanish, Italian, German or Japanese. The nine Les Cars Rouges stops are schelduled as thus:
Stop 1. Tour Eiffel 1st Departure 9.50 - Last 18.30
Stop 2. Champ de Mars 9.55 - 18.35
Stop 3. Musee du Louvre 10.15 -16.45
Stop 4. Notre Dame 9.55 - 16.55
Stop 5. Musee d'Orsay 10.10 - 17.10
Stop 6. Opera 9.35 - 17.25
Stop 7. Champs Elysees-Etoile 9.35 - 17.50
Stop 8. Grand Palais 9.50 - 18.00
Stop 9. Trocadero 9.30 -18.10

You can catch one of the tour buses at any stop every 7 minutes in Summer and every 15 minutes in Winter.
For more info go to; www.lescarsrouges.com
I think you really need a good guide book on Paris that will give you all the details on Paris and make your visit so much easier.

There is more than one company, Cars Rouges is one major one, as good as any, I suppose. It seems to be the one I notice the most now. The other has yellow and green buses, I think, and is Paris Opentour
http://www.paris-opentour.com/

There is no need to book either in advance.

By the time you pay the fare for all the family group, you could hire Michael Osman for a personal all day tour, tailored to your family's needs and wants.

I second Michael. We spend a full day with him in Feb. We were 3 women and 3 teens. We had a great day and covered a lot.

I'll third Michael...unless you want him for the couple of days we've booked him for again.

And how does one contact Michael Osman?

[email protected]

It seems that several people here have hired Michael and recommend him, but no one has ever mentioned cost. Anyone willing to give a range for what he charges?

Ihave always thought it not fair to Michael to tell his fee on the board. Suffice it to say it is VERY VERY reasonable. And it is per day, for however many you have in your party. In my post, I suggested that if that family got on the bus (at 22€ each), it would be cheaper to hire Michael. Do the math.

Sorry, Gretchen, but I can't do the math for "22E X ?"--the OP never specified how many members are in the "family group." I am a solo traveler, so will be paying it all myself. And people's definition of "very, very reasonable" varies widely.

Would someone mind emailing the rate to me privately--my screen name @gmail.com. Thanks, everyone.

This group may be too expensive for some and I have no experience with them but it was recommended in an article in The Times.

http://www.frenchlinks.com/home.html

Okay solo traveller, I assumed at least 4 people.

And believe it or not Michael will tell you himself if you e-mail him.

"And believe it or not Michael will tell you himself if you e-mail him." Wow--really? I never would've thought of that!

Duh, Gretchen. I just have an inherent skepticism about "businesses" that won't post prices on their website. Unless they aren't charging consistent rates, why wouldn't they? I'd like hear what other people paid, not only to find out the price, but whether it is a consistent rate.

Jsmith--thanks for the link to the other tour group. It is little too much for me alone, but I'm going to bookmark it for my spring trip with my mom. The food tours sound great!

What difference does a "consistent" rate make, for heavens' sake? I know that Michael used to charge X and when we went he charged Y. He is dealing in a service and can charge what he wants just as Rachel Kaplan can. She can change her rate tomorrow and put a new figure on her website--consistent price?
We hired Michael for two days--one day for an overview "tour" --I have been to Paris numerous times and he showed us things that day I had not seen. The second day he took us to the Louvre and the Orsay. Absolutely wonderful Our adult children and their spouses absolutely LOVE him. I wish we had lined up yet another day. He has a wonderful way of relating a story or incident in history. Has an absolutely great sense of humor and is SO pleasant to be with. He made some reservations for a special dinner for us in advance of our arrival. Just an all round nice guy.