OP just seen this. Mrs B is Parisienne, we are here now in fact, we know the west side better as thats where we live when here. Glad you went to Sacre Couer st night, it is indeed wonderful. Normal big city advice to keep your wits about you.
Francencour near by is a great little bistro/bar, good for brunch too.
Make sure you walk about, always the best way to see things. The stroll through Garden Tuileries (excuse spelling) then Louvre, the cut down to the river and along to Notre Dams, round the back and over onto Ile de la Cite and then loop back other side of the river for a bit. Eifel tower view from Trocadero.
The refurbushed L’Opera is worth a quick visit
If you can download app La Fourchette for good dinner discounts and reservations