Best time to visit Eiffel Tower

Not everything is closed on Monday, the ET definitely isn't, neither is the Louvre (it's closed on Tuesday).

One of my tips is to take a blank calendar for the time you're going to be there and put each site's day closed on the Calendar and work from there.

Timing for the ET is completely your preference - daytime, sunset, nighttime, etc.

For the first day, you won't be in Paris after CDG until the afternoon, so I'd walk around Notre Dame, the flower market, etc., and take a Seine cruise, the one that leaves just before sunset.

Keep in mind - if you're there 30, 31 Dec, 1, 2, 4 Jan, you're losing basically 1 full days by doing Versailles, combined w going to Belgium, that's 2 full days out of a short trip....

hey hey palciparum
where are you flying from to CDG, where are you staying? jet lag is different for everyone. walking around, no boat rides, keep warm so dress appropriately, water proof shoes, gloves/mittens, earmuffs, poncho. if it rains and cold i'm miserable. have a meal, angelina's on rue rivoli has yummy hot chocolate, pastries, food. your decision on eiffel tower, been once daytime, twice nighttime. get your timed ticket online at website before going.
order what attractions/activities online before going.
dec 30, could be your "jet lag" day. you are there at a busy crowded time, with thousands doing the same as you, plus you are cramming too much in with your short time (2 days "lost" with brussels & versailles) when buying "skip the line" tickets, doesn't mean go thru first, you have a security line all wait & go thru. do you have you train ticket to brussels? buy early and cheaper. you haven't mentioned anytime for eating, if it's rainy/cold eat inside with waiting time, did you reserve dinner places especially your NYE night, any picky eaters?
did you reserve cooking/baking class which will take up half a day.
your trip is too much go go go without stopping to enjoy the paris atmosphere, sit at cafe people watching plus some "free & crazy" sidewalk entertainment.
it's your vacation, you do you and your gang.
aloha

Thanks for the replies.

I am flying in from Dallas. Leave USA evening. Reach Paris morning when it will be mid night in Dallas.

I have booked train tickets to Brussels but have to make bookings for culinary class.

Wondering if I should take guide to see museums especially Louvre (I have no knowledge about art) and Catacomb? Any recommendations?

I would book your ET immediately if you plan on going to the summit. We are going roughly same time and it was mostly sold out except for 10:30PM slots...also, my 14YO is very excited about going to the catacombs, so I would show him/her what it is and see if it's of interest.

You can walk up and purchase.

You could download Rick Steves Europe App. Follow & listen to The Louvre walking tour, 57min. Download it and the tour prior to leaving the states or from the WiFi in your hotel or apartment prior to departing.