I would like to recommend that visitors to the UK take a tour of Scotland
Fly to Edinburgh in August when the International Festival is on and the streets are full of performers, and there are shows to see in every possible venue, for a 'party-on ' experience!
But to be able to appreciate the beauty of Edinburgh, visit at Easter when you can wander up The Royal Mile, exploring the closes and admiring the architecture without hundreds of other tourists tripping you up and spoiling your photos(!)
Princes Street Gardens will be full of daffodils, and the Castle won't be too crowded for a visit. Make sure you climb Arthur's Seat, the extinct volcano in the middle of Edinburgh!
Next, drive through to Stirling to visit the Castle and the Wallace Monument. From there, head to Oban, a picturesque coastal port town, and head by ferry into the Western Isles. I have not visited them all myself, but can heartily recommend Mull, which has beautiful beaches. From Mull, take the five minute ferry to Iona, a beautiful peaceful island. You cannot take your car across unless you live there, and it's all the better for you as it needs to be wandered around.
Harris boasts beautiful white sands, and is where I would love to visit next.
Back to mainland, the Highlands of Scotland are spectacular, and a drive through Glen Coe is well worth it.
Glasgow is a wonderful historic city, and the shopping capital of Scotland, definitely worth a visit, it is one of the friendliest cities I have been to. I also love Fife. Small coastal villages and harbours, it is very pretty. Of course, golfers will have to visit St Andrews. I'm not a golf fan, but it is one of my favourite towns in all of Scotland. It is such a pretty town, and looks much the same as it has done for hundreds of years. The castle, with it's underground dungeon is a great visit, and who knows, maybe you will bump into Prince William!
Elsewhere in the UK, Belfast is one of the most beautiful cities, with it's sea loch. Just up the coast, you must visit the Giant's Causeway, spectacular! If you holiday in N. Ireland, make sure you visit CarrickFergus and have a Maud's Ice Cream!
I agree with others that Cornwall is fantastic. Sitting watching the surf hit the shore at Newquay is fantastic. You must hire a body board and wet suit! But only go in when coastguards are on duty, every year surfers are killed
If you can only go to one place in the UK, London is the
must see. Seeing all those famous places is fantastic, and transport around the city is great! I especially loved Trafalgar Square and London Bridge. I'd love to visit Kew Gardens.