The original Arione is an outstandingly comfortable saddle suited to all kinds of riding. There's a plethora of different versions available, but the original is still the best.
Its length offers a good amount of forwards and backwards room to sit, which helps with comfort on those long rides as you can inch back a little for a different position.
With most saddles you end up sitting back in exactly the same place all the time. The basic Arione without the bar tape kit is £94.99, which is a bit on the pricey side to say the least.