One thing you will have to learn---That is if you haven't realised it already---Is that if you learn to pedal while standing--It doesn't hurt.

You have the common problem of Novice Butt Ache. It will hurt till you get the butt and saddle attuned to each other. May take a while or you may be lucky but it is going to hurt. However- you can relieve the ache by regularly getting out of the saddle for short spells. May be while coasting on a down slope- Maybe while on the flat and you may even have to learn how to climb hills by getting out of the saddle.

Good luck and don't give up on your current saddle till 20 hours of riding have been done.