Do you know which sites we should get reservations or “skip the line” tickets for? I have heard the crowds are getting larger nowadays. I don’t mind a wait of even 1 hour, but do some sites sell out in advance?
Get em all on advance. Why waste time standing in a line to buy tickets when you can buy them in advance online and then you only have to go through security at the time you scheduled to enter?
Purchase tickets directly from the Eiffel Tower:
https://www.toureiffel.paris/en/rates-opening-times
Alternatively, arrive early in the morning when lines are minimal, 08h30 to 09h00. ET opens at 09h30, 09h00 starting 18 June.
There is never a line to take the stairs.