We took one several years ago with a French friend who is a restaurant critic for a French paper. It was very nice , just about 20 tables and exceptional service. It ran about $200.00 a person though.I will admit we drank a lot of wine. No commentary , just a string quartet. Another friend ho lives on a houseboat at Bastille recommended this one . It looks extra nice. http://www.calife.com/

Maybe just at dusk as we like to do is the answer. You start out in the natural light and then the lights come up, and by the time you get to the Tower, it is lit up.
In January it may not be particularly pleasant to be on the river for a long time.

during the day you can also get boats along the Seine that are a bit like buses - get on at the Eiffel tower for example and off at Notre Dame.

they cost even less than the cruise and are a great way of getting around Paris.

Going against the advice here, but we took the Calife dinner cruise in June 2010 and it was really so much fun! You can book one month out and I booked the day our desired date was open for reservations. As a result, we had the first window seat up by the front of the boat. Was the food the greatest I've ever had? No, it was tasty and that's fine as we were going for the overall experience. One could purchase bottles of wine at quite reasonable prices as well. The whole experience was highly enjoyable. They timed it so that you cruise by the Eiffel Tower when it is doing the light show. I would highly recommend it.

Batobus are like water taxis, but with preset stops. Perhaps take one ride on this past Louvre

Nice thing about Bateaux Les Vedettes du Pont Neuf is that you can buy your tickets online at a discount (8€ instead of 13€ at the pier) without having to commit to a specific date or time. Just show up at the ticket booth and trade in your e-receipt for a boarding ticket. I believe they are the only cruise providers that let you do that. This is a major advantage, since the weather is so unpredictable in Paris, and you'll want to do your cruise on a nice day/night/both.

We've always used them.

They're on the western tip of Ile de la Cite where the bridges meet it. Walk across either bridge (from right or left bank) to the Ile and down the stairs. You can't miss it.

SS