Having just flown a week ago Marseille to AMS to USA I looked at flights a bit since this is a SkyTeam routing (Air France, Delta, KLM) and those flights don't work, the earliest AF flight doesn't get you to AMS early enough to catch the KLM flight to SFO. What is Kayak bringing up for you, Air France then WOW? Is this one ticket or 2? Be careful with Kayak or any third party site with convoluted routings. Or maybe you're flying to Detroit or Minneapolis first on Delta, that works.
If you're catching the 6:50 am AF flight you'll want to stay near the airport, can give lodging/food suggestions. It's a long haul to USA from Marseille especially when you get up at 4:30am.
Note that with the state of emergency in France you will have to do a full immigration check leaving MRS for AMS, then a second full immigration check at AMS leaving Schengen.
Birding: you could try Mt Ventoux, also the trails around Pont du Gard, especially after closing (they let you stay late, maybe till 9, ask).
A last comment: we've driven all over France but found Provence driving the most challenging, the plain is densely populated; there are villages everywhere.