2 Days in Nice - Advice

That would be pushing it for me, but you may be able to pull it off if there's not much you want to see in each of the places outside Nice and you plan to grab something for lunch on the run rather than sitting down to eat in a French restaurant (not the decision I would recommend). A few comments:

The Cours Saleya market closes at 1:30 PM on Saturday and is closed all day on Sunday. Although the flower section of the market is otherwise open until about 5:30 PM, the food stalls close at 1:30 PM every day.

I spent quite a lot of time walking much of the way around Cap Ferrat back in 2017. I'm not sure it was a great use of my time, and I was in Nice for 14 days. The problem is that the walkway along the Mediterranean gives views of the sea, but they don't vary much. How much time do you want to spend gazing at water crashing onto rocks? The wealthy folks living on the peninsula value their privacy, so you will see very, very little of their houses while you're on that pathway. In addition, I ended up having to do some scrambling over rocks during part of my walk--the sort of thing that could lead to a sprained ankle. You might consider walking over that path, taking a look and declaring victory.

There are a couple of worthwhile sights right on Cap Ferrat: the Villa Ephrussi de Rothschild (which also has a very impressive garden) and the Greek-inspired Villa Kerylos.

I haven't been to Eze or Monaco. Eze-Village, the very picturesque, hillside-hugging area you want to see, is not a stop on the train line, which only goes to Eze-sur-Mer. You can get to Eze-Village by bus from Nice or Monaco; there may also be transportation up from Eze-sur-Mer.

The rail line is very convenient and inexpensive, but it is sometimes frequented by pickpockets, so be careful of your belongings. If someone gets into your personal space unnecessarily, assume he or she may sell be a thief.

The Cours Saleya market is open Tuesday through Sunday. On Mondays, the flower market is closed and is replaced by a flea/antique market. From mid May to mid September there is a night market in the summer with arts and crafts. You can take the train or bus or VIllefranche-sur-Mer and the Villa Ephrussi does indeed have a large garden with beautiful views on either side of the peninsula. Make some time to stroll down the Promenade des Anglais, or perhaps take lunch on the beach or le Plongeoir (reserve well in advance)

You itinerary is quite doable, although I would consider taking Uber/Taxi to Eze and then taxis on to Monaco (can be hard to get an Uber from Eze and Uber is not permitted yet in Monaco). This can save you some time, versus waiting for the bus schedules in Eze. You can take the train back from Monaco.

Thank you so much. Based on your feedback, and the location of our hotel, I have fine-tuned our plans.

Since we arrive very early on a Friday, I believe we can do the following:

Stroll the Promenade des Anglais
Visit the Cours Saleya Market (try the Socca)
Walk up to Castle Hill - 25 min walk
from hotel - visit Foilles Archeologiques, park, waterfall, views of the city
Descend to Old Port
Explore Vieux (Old) Nice

We are both very active and enjoy walking for hours.

For Day 2, I'm thinking that maybe we should take the bus or train to VIllefranche-sur-Mer and the Villa Ephrussi but skip the long walk at Cap Ferrat (we walked Path of the Gods in Italy and loved it but this sounds much less grand). Lunch then taxi to Monaco for the afternoon and then head back via train.

At the top of Castel HIll, the ruins are not extensive (mostly foundation blocks). The attraction are the great views from the three vantage point. You can easily descend down to the port side. That' a good place to find lunch as well (le Plongeoir at the far end, or in the Port area itself.) Note you will have a walk around the hill to get back into the old town.

For your next morning, yes you can pop into Villefranche-sur-Mer and then walk to the Villa Ephrussi (or take the bus). From the Villa you can take take your Taxi/Uber to Monaco or Eze. (you could try to fit more into the day, depending on how much time you want to spend in Monaco)

i would highly recommend Foodtoursofnice to get a great experience of Nice. Ally takes you places that are not the typical tourist places in order to give you a great overview of life in Nice. I know you didn't ask for a tour recommendation, but this is a small tour and one of the best food tours we have ever done worldwide.