I've been very very happy with the results of WTB Pure saddles:
WTB Pure V Comp - Freewheel Bike Shop - Minneapolis - Twin Cities - St. Paul

That's the cheaper $40 one, though I have the more expensive $90 one. However it does depend on how well your butt fits the saddle, so it can vary greatly from one person to another.

I also have a big butt, and 240lbs, and ride a road bike but relatively upright - endurance bike I usually ride on the hoods, sometimes on the straight part of the bar (even more upright).