It depends on the type of riding you do. Are you riding a road bike, a mountain bike, a hybrid, etc? Your position determines the stress and pressure on your posterior. Casual short distances on upright bikes lend themselves to wider saddles. Long distances on a road bike are more comfortable (for me at least) on a narrower saddle. Sixty Fiver gave good advice above.

Another question is whether whether or not you're wearing bike shorts. I also find that they make a big difference. Be aware that many cyclist shy away from very thick pads and gel seats or bike shorts because they start to feel like a diaper I've been told.

Last question. Are you new to biking? Almost everyone finds bike seats uncomfortable until your butt becomes used to riding.