Ah Paree, the City of Lights, the City of Romance. What can I offer that hasn't already been said? When I was a student, I spent one summer and one spring semester studying in Paris. Last time I set foot there was in 2009. I wanted to go back and see how things have changed. Spoiler alert, they haven't, except maybe for the road that runs along the Seine offering apero and a nice relaxing atmosphere, more on that later.
As a first timer, I'd suggest you'd take more than 3 days to explore this awesome city. As this was not our first, or even second time there, we wanted to do a bit of touristy stuff mixed with local things. I know that we are lucky to have a friend who offered us to stay with her in Marais, but from what I hear, Air BnB is popping. If you want an authentic Parisian experience, I'd say go with the AirBnB option and see locals' apartments.
Musee Rodin is always a must in my book. It's my favorite museum in Paris, small and quite inspiring. Bonus, the lines are incredibly short there as well.
Eiffel Tour, if you feel so inclined. For some reason, I really wanted us to go to the top. It took better half of the day, WAY longer than it used to be, given the ever present threats that France faces. It's still worth a trek.
Sacre Coeur and Monmarte - I always found this area of Paris a bit disconnected from the rest, living on the edge, both literally and figuratively. The church is a splendid sight during the day and the view from the top is pretty cool.
Notre Dame de Paris is BY FAR one of the most awe inspiring French Gothic architectures out there. It's just so beautiful and breathtaking. Going up is easy, but even sitting on the Seine in admiration is all you need.
I came hungry! I was like, that's it, let's eat and there is literally no way you can have bad food in Paris. Even bad food is good, like McDonald's actually uses real meat.
Chez Janou - a delightful find in the Marais with their house specialty of Tagliatelles aux escargots (yes, that's right, snails) and for desert, a chocolate lover's dream, a GIANT vat of mousse au chocolat.
La Cave Gourmande - ever seen that video of Julia Child making boeuf bourguignon (here it is for reference) and wondered what a really good boeuf bourguignon would taste like? Fun fact, Brady once attempted to make with moderate success. But this place, this is the stuff you dream of, your mouth waters when you even think about it. Small, quaint and typically Parisian looking joint with an amazing secret. Try it and live to tell the tale.
L'As du Fallafel - when I was a student in Paris, I was broke most of the times. This falafel joint serves up seriously delicious and filling meal. They are a couple around in the Marais (also known as Quartier Juif - Jewish quarter - but L'As is by far my favorite.
Bars along the Seine - along the riverbank, there are tons of bars that popped up as the highway got closed. If you didn't know, Paris has open container laws, so you can buy a glass of wine and stroll along the Seine, which is what we did.
Let me know if you have any other questions about Paris and I'll do my best to answer