The first thing you need to do is to get the bike properly fitted. There are a number of good videos on the web (and some not so good) describing the DIY procedure. If anyone has a link to a good one, please post it. It helps to have a small level, a yardstick (to judge alignment more than to measure), a tape measure and a homemade plumb bob (a small weight on a 48" string). A friend, preferably with cycling experience, is a big help during the DIY fitting. The DIY will get you close enough to get started and you can fine tune after you put on some miles. Without a proper fitting, no seat will feel comfortable for long. If you have any problems, your LBS will likely offer a basic fitting for a nominal fee if you tell them you are buying a saddle.

The mistake many people (myself not that long ago included) make is to think that big, cushy, gell-filled seats are more comfortable. It may feel that way when you first climb on but it doesn't take many miles before that bar stool seat starts working against you. Another mistake is to ask other people what their favorite seat is. Every rider is different and the seat that is perfect for someone else may not work for you, no matter the expense or reputation.

Get a seat that fits your sitbones (the ischium of your pelvis). I don't know your body type, but just in general, some heavier riders think they need bigger seats and that is not always the case. I'm a bigger rider and I found this out the hard way. Seats with smooth, gentle curves reduce rubbing points. I also recommend looking for a seat that doesn't have a crowned profile where it it highest in the middle of the seat. Most modern seats are relatively flat on top and some have recessed or cutout areas to reduce pressure spots. Your weight should be on your sitbones, not your privates, and the seat should not press hard on the inside of your thighs (this is the reason you don't want an extremely padded or overly wide seat). Once you have your seat on the bike, start with it level from the point of contact for your sitbones to the highest part of the nose. Move the seat back or forward until your kneecap is directly over the center of the pedal in the 3 o'clock position. You may have to fine tune but this is a decent starting place. Don't ever have the nose of your saddle higher than your sitbones or your "womanly parts" won't be happy. Very slightly nose down might be OK, but is usually unnecessary if you have a good saddle and proper fit.

Take some test rides on bikes at the LBS just to try out the seats. a 5-10 minute ride isn't a great way to judge an endurance seat, but it at least points out glaring problems. There may be a little trial and error before you find the perfect seat.

WARNING: If any salesperson suggests a noseless seat, back slowly toward the door while avoiding eye contact and then run for it.