Headed to Europe December 14 - January 6 (4 adults) Where?

You have unlimited options (well, maybe limited by time and/or cost), but we had a fantastic trip 5 years ago at that time of year.

I'll bet you can find cheap flights from London to Rome (which might necessitate transferring From Heathrow to Gatwick or Stanstead airport). We spent an affordable, enjoyable, uncrowded, not-96-degrees-in-the shade December week in Rome, then flew to Sicily for the next week. Sicily has a few cities, but it's mostly countryside, with ancient Greek and Roman archaeological sites, fabulous mountain scenery, a few museums, incredible food, and again, in December it's not unbearably hot or crowded! We were on the move, driving a rental car in a counter-clockwise direction. We actually skipped the city of Palermo (the airport was many miles west of the city itself), but visited Erice, Agrigento, Syracusa, Modica, and lots more. The highways are toll-free and easy to navigate. Some country roads are narrower.

Rick doesn't include Sicily in his guidebook, but he did film a Sicily episode years ago, and inspired by that, and relying on a great Lonely Planet guidebook, we had a relaxed yet full experience. We spent Christmas Eve and Day at an agritourismo B&B featured in Rick's video, and they hosted a lavish early-afternoon Christmas feast attended by locals from miles around.

We wrapped up our third week back on the mainland, driving up the boot to Sorrento and the Amalfi Coast. Again, not crowded, not too hot, and all wonderful. Much of mainland Italy could be done by public transportation, but for Sicily, if you want to see much, a rental car worked best for us.

Italy for best weather and culture and affordability.

See, here is where we can disagree on the most basic principals. Italy is a big country so "the weather is better" is sort of an overstatement. In the north, maybe, in Rome it stinks. Too cold to be warm and too warm to be cold and very little winter culture, just hunkering down till things warm up. As for affordability, again, very large country ..... Rome can be expensive as can Milan and Florence and ..... but i am sure the smaller hamlets are more affordable.

Its Christmas season for G-d's sake. Go where they do Christmas and Winter with class and style; Central and Eastern Europe. That is if you like the lights, the markets, the theater, maybe a little snow and cultures that know how to make the best of the winter (they had to figure it out as the winters are long and cold). Naturally i am predisposed to Budapest, but any place from Germany through Austria to Budapest and even east to Ukraine makes for a good option. Extend your trip a few days and do two Christmas', one Western and one Eastern Orthodox.

If you like Prague, then do Prague. Then find a discount nonstop one way flight to the next destination; a destination that has a nonstop discount connection back to London. I do this a lot and I use Google Flights to find the flights. With Google Flights you can use Prague as an origin and EUROPE as the destination and all the options and costs pop up.

Be careful where you plan the two weeks from just before Christmas until after New Year. Different countries, and often different parts of the same country, celebrate the two big events differently, even on different days of the year. Many places will shut up tight - like a drum - for some or all of that period so that they can spend them with family and friends.

London is one of those places deader than dirt on the 24th, 25th and 26th. I've done a few places in Central/ Eastern Europe for both Christmas' and found enough functioning to have a great time. Probably could have in London too if I had looked a little harder. I generally expect that from noon on the 24th till noon on the 26th I will have to rely on tourist venues and higher end restaurants etc.