How many days in Prague?

Two days as the first day, arrival day, you’ll be jet lagged.

Ditto Suki

Hi from Wisconsin,
You either can't stay 3 or 4 days extra, or you think you will run out of things to see and do. I would go for as many days as you can afford. The sights you know about are sights most everyone knows about. And Rick will surely take you to many of them. Expect tourists.

What to do? A stroll around the Loreta and its sights, then through the castle which you will see with Rick(?) and continue through Letenska Park (provides top down views of the old town and greenery) ending at an open air bar and the Museum of Technology. That can fill a day. The museum is in a nice gentrifying neighborhood lacking only tourists. A good selection of restaurants awaits you there. The Farm is in a ways and is a farm to table restaurant with unique offerings. Cafe Letka of course has coffee, but some interesting companions for coffee. Ristorantino da Matteo has some cutting edge Italian for you. There is also the National Gallery of Prague tucked in this neighborhood. This area is called Letna. A place to stay, Letna Garden Suites, from $70 to $200 depending on dates.

Buy Ivana Edward's Prague Walks, under $10.00 on eBay, before you go and do the walk that takes you through the Bazilika of Sts Peter and Paul . The cemetery is like an art museum. The walk ends in the cubist neighborhood.

So many things to do.
wayne iNWI

I would say at least two full days ahead of time. Unless your style is whirlwind. Lots to do. You could spend a whole afternoon at the Letna park beer garden. All outdoors under the trees with a great view. You could go to Vysehrad castle and walk the walls. Great views. You could go up Petrin park hill. Climb the tower. The hall of mirrors is there.
You could visit the miniature museum. See a grain of rice carved into a carriage. While this may sound trite, it is a pretty good museum.
You could eat a pig knuckle. And you should.
So unless you have few interest or are bingeing rapidly around the city, only stopping briefly anywhere you go, you could use those extra days.
A tour is good to see a lot of different places, but one and a half days in Prague?

Our last trip before Covid was to the Czech Republic in the fall of 2019. We spent 9 days in Prague and never ran out of things to do. One of our best decisions was going on the Taste of Prague food tour. The time spent on the tour itself was fantastic (as most food tours are) but the overall most rewarding part of the tour was experienced after the tour was over. One of the goals of the tour was to educate you about the other parts of Prague that are outside the touristic center. They have a good-sized guidebook that they update regularly that lists all of the best spots... to eat (broken down into categories such as splurge, breakfast, dessert, etc.) drink, shop. Also included are several neighborhood walks, including what to see, where to eat etc., so we explored much more of Prague than we usually do when we are in a larger city. If you take the tour the guidebook is free, but you can also download it from their website for less than about $10.