This is my Post-Trip Update (my questions for the trip are on the Slovakia forum).
Thank you to everyone for your suggestions. We had a good trip Sept 4-16, 2022. I ended up using guides that people recommended. In Prague, I hired Jason Holt (Living Prague) as an all-day guide for my first day. Later that week, a group of us had a Prague city walking tour with the guide company from our 2015 visit (PragueWalkers, recommended by RS). And in Slovakia, we hired Michal Razus, a recommended guide/genealogist, for two & a half days of traveling around the Presov region.
In Prague, Jason was friendly & generous to work me into his limited time that week (he was going to England for a visit). I joined his morning group for a walk around the old city & Jewish quarter. Good intro. Jason even invited me to join him for lunch with his delightful Scottish friends! Great guys. Felt like lunch with old friends. Then Jason did a shortened walking tour with me during the time he had left that afternoon, covering random topics (WWII, architecture, history, modern life for Czechs) as they appeared. Interesting to hear his perspective as a British man in Prague and to be able to ask all the questions I wanted.
PragueWalkers provided Gabriella for a 4-hour walking tour later in the week with us and my husband's cousins. It covered a lot & was flexible since it was a personal tour. Some descriptions went a bit longer than was helpful but it was a positive experience overall. Even in occasional downpours of rain.
In Slovakia, a guide was absolutely essential since it's a little harder to get around without the language. Michael drove us around to various historical sites (a cool castle in Lubovna, a medieval town called Bardejov) as well as sites covering my Carpatho-Rusyn heritage (museums, wooden churches, etc) and local food places. Our discussions with him about everything from history to modern life in Slovakia were invaluable. A very friendly & thoughtful person. Presov was our base & proved to be a very walkable small historic town. We were almost able to deliver supplies to Ukraine when Michael introduced us to a local nonprofit he works with. That would have been fantastic (unfortunately their schedule changed & it didn't work out). We spent our last day in Kosice--a historic town nice for a day of strolling--and flew out of there on a 5:00 a.m. flight.
Both Prague and Slovakia were incredibly affordable relative to other places in Europe. It was also helpful that the dollar is almost even with the Euro.
The Slovakia issue: I can understand a little why Rick Steves does not recommend Slovakia yet for tourists, even if I don't totally agree. Yes, it's a little harder to get around without the language (which is a tough one) & the infrastructure can be a little rough around the edges, probably given decades of communist rule & their crazy 20th century roller-coaster history. Landscaping isn't valued. Soviet-era architecture can be ugly outside the thin veneer of beautiful old city centers. Sometimes things aren't organized well (i.e. a museum where the audio guide doesn't match what you see). Lovers of pirohy will be happy but others probably won't be writing home about Slovak food. Slovaks are often painfully aware of their low economic status in Europe--and often fatalistic (like most Slavs) about things improving. YET there's beautiful sights & scenery in Slovakia & lots of history, especially if your ancestors came from there. Moreover, meet the very friendly & personable Slovak people. Make any pathetic attempt to pronounce their language & you will get a smile. They love to chat. They're also very faith-filled which is a wonderful thing to share in for those of us who do. They love their home & they should. Maybe if more people visited Slovakia, the rough edges for tourists would soften & it would become an easier place to visit. So visit!