How long does she plan to spend there? $3k should be easy for a week or two for two people if she is flexible with her dates and can book tickets using miles.

On-the-ground costs of accomodation, sightseeing and food can easily be kept under $200 a day for two people. Get an apartment off airbnb.com, make the occasional meal at home, eat out at cheap places like maoz, make do with a bageutte et fromage lunch, buy drinks from the supermarket, use the metro instead of cabs (that's what Parisians do), and try to visit the museums when they have free admission.

Others can chime in with CC recommendations to get miles but I think the Chase 50k Sapphire Preferred and Ink Bold bonuses should cover you. The Ink bold bonus expires on Nov. 28th so hurry.

People often get CCs for hotels here, but in most cases I find those to be poor value as I don't value staying at the Ritz any more than I value staying at a nice $100/night apartment. But I guess they can save you money if you don't want to do apartments...