Marseille airport

Your airline should give you a check-in deadline. Flights within Europe allow shorter check-in times, for instance if you make a connection in Paris or Amsterdam before boarding a flight to another continent. I have not been to Marseille airport, but Rick's book calls it "small and easy to navigate." Lines to pass through security checks can take just as long in France as in USA.

Give yourself a good time cushion. It is quite a way out of town and expensive to get there if you do not use public transit. I would not agree that it is easy to navigate. Not my favorite airport by a long shot. TC

As TC says, travel time to the Marseilles airport can be substantial, depending on what method of transport you use, time of day, where you're coming from.
It's 12 miles northwest of the Marseilles Center, and the travel time can be substantial, depending on how you get out there.
You'll want to plan for getting out there and allow sufficient time.

I plan on staying overnight at a hotel near the airport, but didn't know if I really needed to get to the airport two hours in advance as they suggest here in U.S. for international flights. I will be connecting in Brussels.

I just checked with Brussels Air and was told I need to be there two hours before my flight. That puts us in the airport at 4:40 am - wow.

In June 2013, we had an early flight leaving Marseille at 6.25 and connecting through Brussels for our return to the US. We stayed at the Holiday Inn Express-Vitrolles, which also seems to call itself Holiday Inn Express Marseille Provence Airport. It's very close to the airport, and there may even be a shuttle. It was fine for us and I would recommend it for you and the grands. There is a hotel pool and light food on the premises.

I remember cruising through security pretty quickly and having a lot of time to kill at the gate...

Good luck and have a great trip!

Thanks to everyone for the input. This website has been a wealth of information.

You did not ask about staying near the hotel the night before but I highly recommend that. If you decide to do that, I suggest the Pullman Marseille Provence. It has a free shuttle to the airport. Recently, I took a 6 AM flight from Marseille to North Africa and arrived at around 4:45, which was late and we were nervous as we arrived at the airport but it all turned out well. It's a small airport so getting around it is pretty easy.