perhaps the best saddle for long distance riding would be a Brooks, specifically a Brooks B17. They are traditional leather, and need a breaking-in period while they are still new and hard. But after that, it is the most comfortable saddle around, and countless long distance riders use only Brooks. (There are of course people who don't like them.)
As for tyre pressure, it depends to a certain extent on the tyres you are running, plus your weight. EG if they are narrow like 28mm, then they require high pressure to prevent pinch flats, but should be fine at 60psi for an average person. That will give about the same sort of ride harshness as a high pressure (>100psi) road tyre. Wider tyres are rated at less pressure and should not be pumped beyond their rating or you risk a casing failure.
For a really comfortable, easy-rolling option, you could go for Schwalbe Big Apple tyres; they are 50mm wide and are run at low pressure eg 30psi; but their design is such that there isn't a penalty in rolling resistance.
Adapt your riding style as well; try to take more weight on your legs as you roll over bumps and stuff. This the first line of improved comfort.
Enjoy your ride!