Just because you'll sit on the seat for long doesn't necessarily mean you'll need extra padding or width. As experience increases, so will the need for a narrower and firmer saddle, generally speaking. The same happens as your riding position becomes more bent-over.

Everyone's tush is different, so you have to do some experiments to figure out what's good for you.

I'm very suspicious of the high-priced Italian style saddles. By Italian, I mean a plastic shell, padding, and a leather or vinyl cover. A $30 saddle seems just as good as a $100 saddle. I have had some wonderful rides on $30 saddles. And they all wear out.

A Brooks style leather saddle can be worth the money for fit and also for durability. If you take care of it, it will last a very long time.