Saddles are important because if you choose the wrong one you'll be sore. Make sure it has a narrow nose and a standard-width back. If the nose is too wide it will rub the insides of your thighs. Avoid extra-narrow mountainbike saddles; they allow mountain bike riders to slip their weight easily behind the saddle on steep downhills but the loss of contact area can become painful quickly. There are wider saddles for women, whose pelvis is shaped differently.
Surprisingly, feeling the padding of a saddle for softness does not say much about whether the saddle is comfortable. Saddles usually consist of a hard shell, padded with foam with a flexible plastic cover. The thickness of the foam padding does not make a lot of difference for comfort because there are only two small contact points where bone meets the saddle. Even gel padding is only marginally better than foam. It's more important whether the plastic shell is completely rigid, which is not good, or whether it is flexible and held in shape by the two rails that the saddle is mounted on, especially if these rails are themselves flexible.
Some people swear by leather Brooks saddles, which work by the same principle except that the leather stretches more than plastic and so the rail mounting needs to be re-tightened occasionally. The leather needs to be rubbed frequently with oil at first so it is soft enough to change its shape to adjust to the shape of your pelvis, and must be protected from rain. Once you get past the initial months it's said to be the perfect saddle, but I prefer not to go through all the trouble.
One of the best saddles I have used is the regular racing Flite, which has next to no padding but a flexible shell and soft Titanium rails. I normally avoid the Titanium hype but this is a really useful application. Titanium is much softer than steel. Unfortunately you can't adjust the tension, so after a couple of years it sags and becomes unusable.
My favorite is the Selle Italia Turbo Matic 2, with its distinctive yellow/black rear end. It's the best of both worlds, and I have done many long tours with it.
The saddle height is very important. If it's too low, you have much less strength when pedaling, and if it's too high you'll rub your thighs sore. Adjust the height until you can pedal backwards with the heels of your shoes on the pedals, with fully stretched knees but still touching the pedal when the pedal is in the bottom position, without rocking your hips. The position must be exact to about five millimeters (1/5 inch). I prefer the standard angle where a bar laid on the nose and back of the saddle, parallel to the top tube, is horizontal, but some people prefer the nose slightly up or down.
See also an article on "Bicycle computers"
