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 - jut check when booking.
The time to visit, from my experience, is definitely November / December when the temperature is not dissimilar to the UK, although it can get quite a bit colder. Sitting in the old cobbled streets, supping a beer under heated umbrellas and watching people walk by is great.
Beer drinking aside, which incidentally is not an expensive pastime even if at a touristy location, there are obviously a lot of great sites to see in Prague and if you like architecture and history you couldn't be in a better place. Some of the key places to visit, which you can do on your own or as an organised trip,
The Old Town Square - the site of the astronomical clock which chimes on the hour - well worth seeing and with numerous stalls selling mulled wine, roasted chestnuts etc there is plenty to keep you occupied. You can walk, or get the lift, to the top of the tower on which the clock sits - the views are fantastic!
The Charles Bridge - a fantastic old bridge which gets packed with tourists and locals alike, and on which painters, musicians, jewellery makers etc all sell or perform. A fantastic place, if not a little crowded at times, but so worth it - amazing it has been standing for so long.
The Castle, and its easy to see it on top of the hill as it is so big, along with the Cathedral is fantastic, and with so much history - to get the most out of it if you want more than just the sights then take one of the many guided tours on offer from the town centre.
The Jewish quarter, where we were told on our tour the Gollum was "made" - Don't know much about this area as unfortunately ran out of time but told that to appreciate fully a couple of hours was required - something for the next visit.
Just walking around Prague's cobbled streets window shopping is a pleasure, although have to say getting lost among all the narrow streets tended to happen quite a lot, but not really in a hurry anyway so it was of no matter.
Finally - best time to go is during the week, as opposed to weekends, purely due to the number of people or as we did, go on Wednesday and come back on a Sunday - best of both worlds then.
Enjoy!
Dave M