Prague to what 2nd location advice

hi everyone! my fiance and i are flying into prague this august for a full week! i’ve been to prague before but my fiance never has. we were hoping to combine this trip with another city or country. it’s also our 30th bday so we wanted to do something extra special for that! any advice on where to go?

we are open to trains (if they aren’t too far), night trains (for further places), flights (if under about 150), and renting a car to drive!

we love beautiful scenery, relaxing by a body of water with a cocktail and a good book, good food, and cute cobblestone towns. we are less interested in busy cities, but open to anything.

thank you so much in advance!!