Lille is a great Christmas town, and a great market there too....the rest on the tunnel is good, for a quick half hour, but as you know, I did a 1000 mile trip in 14 hours and loved the drive.....
I envy you going to Paris, if your Mrs wants to go shopping, park up by Opera and visit Gallerie Lafayette and Printemps.....great department stores, and Printemps has a lovely restaurant in the top of it.....