We are planning a last minute trip to France for a wedding. We are flying into Amsterdam for 5 nights and we have 9 nights in France until we need to be in Cannes for 5 nights for the wedding. Flying out of Nice. We do not want to see Paris spent 10 days there on another trip. We were thinking about taking a train to Paris, pick up a car and split our time between the Loire Valley and Lyon. Open to any recommendations.

I loved Lyon and thought it easily worth 4 or 5 days. And I'm sure you realize that there's a LOT to see between Cannes and Nice. I found the Michelin Green guides especially useful for these areas, The Loire, too, but it's been too long since I've been there to offer useful comments on that part of your itinerary.

You might find some useful information about the southern coast and Lyon in my trip report. It's long, but searchable; look for purple text marking specific locations / issues.
A stellar month in southeastern France

Have fun planning! You'll see some wonderful things no matter what you choose.

Drive to Provence from Nice. I have been over and over and never tire of it. St Remy is a great town to stay in. So many gorgeous charming villages. Too short of time to go back to Paris and tour Loire Valley and Lyon. Enjoy slower travel and stay closer to Riviera. I can recommend more if you were to be interested.

We spent 10 days in the Canne area on a previous trip. Will check out your trip report

time of year, how many people are we?

Any special interests? Castles, cycling, wine, technology, meeting with people, dancing, canoing, sailing, rock climbing, summer luge, hiking, opera, pottery, bell making, choral music, playing games, bread making?

Aside from Provence, Auvergne is my favorite region of France. It is an ancient volcanic landscape of green verdant valleys punctuated by black lava outcroppings. Also called La France Profonde as it seems untouched by influences from other cultures. Imposing chateaux, farm visits, hikes to craters, and a unique food culture and architecture. Anjony, Orcival, Salers, St Flour, Aurillac, Le Puy en Velay, Polignac. Le Puy is a super site, among the highlights of France.

This is a pretty good rundown:

https://www.planetware.com/tourist-a...-f-auv-auv.htm

I don't remember who it was here, but about six years ago we followed advice to visit Le-Puy-en-Velay as we looked for a good driving route from Provence to Amboise - and it was one of the highlights of our month-long road trip in Provence and the Loire Valley. Highly recommended!