Bring gf (and lotsa money) to Rue de Cambon for shopping. Eat at
Monmarte or around Latin Quarter for its plethora of quaint
choices, both very nice and romantic at night. For sightseeing,
just walk and explore. It's a great walking city and the structures
are so big you can't miss them. Of course, if you want to check out
a museum, the Lourve is the top choice. But it's so big and
overwhelming you may not have energy to enjoy the rest of the day
(be prepared to spend at least 3-4 hours there just
browsing).
On a more practical note, the transport system is great. There are
train stations within 500 metres of each other so you can't really
get lost. It's not a cheap place but neither is it expensive
(food-wise). Parisians are quite alright in my opinion, no bad
experiences, and service is always good.
But all in all, you will not be able to cover much of Paris in that
48 hours. I've been there twice and I've only explored Paris north
of the river, still haven't explored the south (university)
side.
Hope you enjoy yourself! P.S. Weather is abit erratic this part of
the world currently, be warned. It can get really cold
suddenly.
