Here is my top 10:
1. Wander about Prague Castle ground and marvel at the vew.
2. Join a bike tour and you will see different parts of Prague
3. Take a stroll in the Royal Gardens. Spring is a good time for this, when the tulips and other flowers are in full bloom
4. Drink beer in one of the beer gardens. A good one is U Medvdicu.
5. Dine on the top floor of the Dancing House and marvel at the view.
6. Have a coffee in Kavarna Slavia and enjoy the view of the Vltava River and Prague Castle beyond.
7. See an opera performance in the National Theatre. If you don't like opera, go anyway to see the beautiful interior.
8. Have lunch in Art Nouveau style in Hotel Central at Wenceslas Square.
9. Climb the miniature version of the Eiffel Tower.
10. Eat Prague sausages with a big dollop of mustard at one of the sausage stands.