Agree with Eurostar being a good way to do it (although, curiously, I still like flying on this route - there's something about the crumbling avant-garde architecture of Roissy Aérogare 1 that always makes me grin). First class on Eurostar gets you an inclusive meal, which, although far from Parisian restaurant quality, is surprisingly good for on-board food.

I don't know the timing, but one of the major pains I have going over there for a weekend is that I often arrive at about 9 or 10pm, which is too late (once you're ready to go out) for many restaurants. If this is going to be the case, there are good restaurants open late (particularly around the 1e), you just have to know where they are in advance.

Failing that, what would I recommend? If you're the kind of person who 'must see' the tickbox sites, then certainly, do that. Personally, I just like picking an area (get a guide like the Time Out that explains the character or particular areas to you), walking a bit, stopping for coffee and maybe a snack, and walking a bit more...

It can also be worth picking up a copy of Pariscope to see what exhibitions are on that weekend. There was a fantastic Rineke Dijkstra exhibition at the Jeu de Paume a couple of weeks ago, for example, and there's so many spaces for this type of thing in the city...

As far as food goes, there are two options, really. Either you go to a relatively well-known, top-end restaurant. Or you find some Parisians who can recommend you a top-quality local restaurant. Everybody has a favourite... There are some areas you can go and pick them off - r des Cannettes in the 6e isn't bad for this, for example, and it's a nice walk down there along r St André des Arts from St-Michel.

But basically... Eat, drink, wander.