Hotel Costes is very very cool, and very very minimal. Fairly expensive though, maybe 400? a night at least. There is a sister hotel, called the Costes K which is still cool and minimal, but costs less.
George V, Ritz, Bristol, Prince des Galles, Plaza Athenee all old school 5 star(grand and ornate). Big beautiful rooms though and great locations.
Visit the Baccarat crystal museum/shop - totally mindblowing. The catacombs are supposed to be worth a trip, although haven´t done it. Walk down Boulevard St Germain, and from there to St Sulpice church, which is very beautiful but probably packed out as it´s the one in the Da Vinci Code.
If you´re only going for the weekend, rule out The Louvre. Too much to see, unless you can shortlist works you want to see and just go to those rooms.
Chez Benoit is a beautiful bistro near Pompidou centre, very french, good for lunch. Also near there is the Pied de Cochon, another Paris landmark restaurant, not as good tho in my opinion, although it is open virtually all night, so quite fun at 2 in the morning.
Watch the beautiful people at the bar in the Plaza Athenee.
A must do is a restaurant called Chartier, which is near Boulevard Haussmann (IIRC), just the best french bistro in the world. Like stepping back in time to 1920´s Paris. The rudest Parisian waiters you will ever meet, but the best atmosphere. You HAVE to go.....
Samaritaine is a beautiful department store, I still remember the christmas lights from when I was about 4. Sells everything, DH goes bonkers in their hardware department.
Bon Marche has the best food hall, fun to go and buy a picnic to eat out somewhere.
I love Paris, don´t find it that dirty apart from the dog shit, hope you have a fab time, we´re trying to go too between Xmas and NY!