Prague, Czech Republic
If you can and have the time then a visit to one of Europe's most beautiful and historic capitals is a must. Prague is one of the most visited cities in Europe, with flights from the UK becoming accessible from more and more airports, and prices, if you book in advance, being very competitive.
There is a wide selection of places to stay once you are in Prague, from top end hotels to self catering apartments. These are available with a central location or a little further out, but don't worry if you are not in the middle of things, the public transport in Prague is good, the city isn't huge so transport times if you are outside the main centre are not excessive - just check when booking.
Karlovy Vary, Czech Republic
Karlovy Vary, or Carlsbad as it was formerly known, is an important Spa. The town boomed in the 19th century and many of the attractions date from that period. So even if you are not interested in thermal baths, the town is absolutely worth a visit.
In the second half of the 19th century many metropolitan style buildings were erected - proud bathhouses and hotels, the Town Theatre, the savings bank, the post office, churches.