The Louvre is undoubtedly one of the greatest museums, you would miss out not visiting and seeing the iconic pyramid by I. M. Pei. The included Musée des Arts décoratifs shows great fashion and design exhibitions, too. Also iconic is a walk through the Jardin des Tuileries, where you find the Galerie nationale du Jeu de Paume and the Musée de l’Orangerie with the big water lily paintings by Claude Monet. The huge, historic Palais of Opéra Garnier also is not too far away.
Close to the Louvre you find all the designer stores on Rue Saint-Honoré, around Place Vendôme and Place du Marché Saint-Honoré. Galleries Lafayette is also a highlight, of course. Here you find all new designer clothes, almost two hundred brands of Champagne and you can go up to the rooftop for amazing views of the city. Close by you find the concept store Nous and the exclusive vintage store Didier Ludot in the beautiful Jardin du Palais Royal.
Dining in Paris, just like everything else here, can be exquisite but also expensive. However, if you find the right restaurants you will have some amazing meals, truly enjoyable experiences and just a lot of fun. Restaurant Verjus is a great example. Their kitchen will surprise you with some absolutely delicious, playful dishes and wines. They also have a lovely, cozy private room for smaller groups. Restaurant Ellsworth by the same team is also close by.
Maison Plisson is a good cafe and lunch spot with an exquisite deli and market hall. Cafe Wild & The Moon and classic cafe La Rotonde St Honoré are also nice. Not really an insider tip but the macarons at Ladurée are just a pleasure, either go to the original store near Madeleine, where you also find the traditional Cafe Pouchkine, or visit the lovely Ladurée cafe on Rue Bonaparte. Also a great place to snack, drink and dance, especially on a sunny day, is Rosa Bonheur sur Seine, a boat on the water edge with perfect views of the Eiffel Tower, Louvre and the activities on the river Seine.