I did the Yorkshire 3 Peaks as training for a hilly race. Despite being end of July, the weather was horrible, it rained all day and it was pretty windy at the tops. But thank to the bad weather, there weren't so many people on the route, which can be quite crowded at this time of the year. The route itself is beautiful and I bet the views are pretty stunning on a sunny day.
I did it unsupported, carrying all my food and water for the day.