Absolute madness, but my passport seems to empty!

I was thinking of either CDG or LHR/LGW for a quick mid week get away - familiar with London, but never been to France - can get to either easily enough and I have an Aunt who lives in the latter and a sister with crash space in London - is it better to fly into London and do a day trip to Paris? or fly into France (cost wise)?

I'm ALMOST getting brave, but I'd like the input of my fellow non revs!