Paris activities - reservation needed?
 

Our trip to Paris is less than a month away. We will be getting Museum Passes.
What activities should we make a reservation for ahead of time and when?
Here's a quick list.
Seine cruise or Illuminations Tour on a Saturday night
Walking tours with local guides
Versailles tour, maybe with Fat Bikes tours

Also, we are a group of 5. We will be there July 7th - 13th. Will we have a problem getting a nice, delicious, but not overly expensive, dinner without a reservation? Any good recommendations? We are staying in the 11th, but are open to a little travel for a good meal.

Any other activities we might be interested in doing that would require reservations that I may have forgotten.

Thank you very much for any help you can provide.

You would probably be more certain if you made dinner reservations. Don't buy any passes before arriving--they will just be more expensive.
You can do a Seine boat ride without reservations--you can print a discount coupon on the internet.
Tours I can't help with--I think they are largely overpriced for what you "get".

Walking tours with companies such as Paris Walks do not take reservations unless it's for special walks. You just show up.

At least stop in to the restaurant the day you want to go to see if you can make a reservation for later; go early, if you don't have a reservation!

I think the only thing you need reservations for are dinner. Everything else you should play as it goes.

If you plan on going up the Eiffel Tower, you can buy tickets online. You are locked in on a day/time of your choice, but it will save a lot of time to not stand in line.

We use http://www.vedettesdupontneuf.com/ and buy the tickets online. It saves 5 euro pp, and you can go any day/time you choose. Just show up with the printout at the appropriate window and you are set.

We have done a cooking class, which definitely needs reservations. We used Cookin With Class and very much enjoyed it.

The only problem with reservations for outdoor activities like the bike tours is what you do when it rains. Would you enjoy biking in heavy traffic in the rain? I would wait for things like that.

You can possibly reserve the bike tour without paying in advance - if so, I would do that. You can cancel in advance if the weather is not cooperating.
The boat cruises are many and often, no need to prebook.
An Illuminations bus tour - you might check on that after you get there for a subsequent evening. You probably have to prepay to reserve that.
Seating 5 could be tricky if you try to walk in during dinner hours - - for places you really care about trying, you should reserve at least a day or two in advance... for wildly popular places, a week or two. Large brasserie type places are a good fallback if you are just looking for somewhere to get seated.