Carol and I had the pleasure of staying in Paris for a long weekend seven years ago now. It was our first vacation together and only went there really to see the Chili Peppers play.
Beautiful city, I would highly recommend it.
Eiffel tower first obvious thing to see, I wish we had gone closer to it at night to see it lit up.
Get on one of the big taxi boats along the seine that go past Notre Damme and turn around at the tower. You get the tickets from machines by the river, like train or tram tickets and we were surprised how cheap they were.
Sacre coeur, where all the caricature artists hang out. Bit of info here. I had always planned on having Carols done, though I kind of got ripped off by letting the first one we came to do it. I do not regret it, though paid too much, as after we'd had it done and sat on the steps at the front of the Sacre Coeur another guy did one for a fraction of the price and it was how I wanted it to look.
Not sure how macabre your other half is though we spent a fair bit of time in Paris cemetries.

Saw Jim Morrisons grave. Also the catacombs under Paris I would recommend.
This is where we stayed, it was part of a package with flight from some site, not sure which now and was very reasonable. Infact we were amazed with the Hotel. It is quite small though was a stay of a lifetime.
We have been away every year since, to different places and Paris to this day stands out as a fairytale outing.
I hope you are able to go and if you enjoy it if only half as much as we did, I am sure you will be happy.
B.t.w. We have very little cash and went B&B only. We ate bread and cheese, or ham for a few meals.
*Edit. We ate one evening
here, the best meal I have eaten anywhere. The guy there was excellent and went through the whole menu explaining in English, very hospitable and welcoming. Tiny place around the corner from where we stayed. Magical.