Eurail should probably be good value yes. Eurail coverage works by train companies and the vast majority of European trains are included. Some exceptions :
- low-cost competitors like Flixtrain
- mountain railways like Jungfraujoch in Switzerland (you often get 25-50% discount)
Amsterdam - Prague is a very long journey by daytime trains. Take a look at the convenient European Sleeper linking the two → https://www.europeansleeper.eu/
22:34 departure, 10:56 arrival (running on Mon, Wed, Fri). With Eurail expect to pay 88€ for 2 couchettes or 258€ for a private double sleeper. It’s a bit expensive but remember that you’re spending the night travelling a thousand km!
Switzerland : Eurail is really good value there as regular tickets are expensive. Boats on Lake Thun and Brienz are fully included and (newly!) trains from Interlaken to Lauterbrunnen, Mürren and Grindelwald too. As said above 25-50% discount on mountain railways/cable cars.
Reservations are mandatory on Italian fast/high-speed trains. Availability a day or two in advance shouldn’t be an issue as trains are frequent. Have a look at https://www.seat61.com/interrail-and-eurail-reservations.htm
Questions welcome of course!