Well worth grabbing a bottle of wine and blanket to go sit on the lawn for the Eiffel tower light show and enjoy the evening. If you don’t bring your own wine there are plenty of opportunities to buy one! It’s almost like tailgating–people get there early and party. People run around hawking Eiffel towers that light up–wish I’d bought one!
No idea if this affects you but when we went the entrance and ticketing to Saint Chapelle was on a totally different street than where it was located due to closed offed areas to Notre Dame.