Ben Nevis
Britain's highest peak (7hrs)
Ben Nevis is Britain's highest mountain (1,344m/ 4,409ft), which makes it a fiercely popular challenge. Some 100,000 people attempt it every year.
This generally makes it a bit too busy for quiet communing with nature, but it's a great hike all the same. And it's doable by anyone who's fairly fit – at least when conditions are good (check the weather) – but don't skimp on equipment (waterproofs, food, water etc).
Also bear in mind that the summit is frequently misty – which can make navigation difficult and dangerous (700m-high cliffs await!) – and snow can fall on pretty much any day of the year.
In winter the ascent is a very different and much more dangerous prospect. Every winter, people are rescued off the mountain.