^^^ is in reply to Igo, but I must have forgotten to reply with quote.

Thanks for all the replies. There doesn't seem to be one catch-all solution, but the gist is that it's not normal for the saddle to cause pain, that I should make some bike adjustments and engage the glutes and core. I think I'll tilt the nose down ever so slightly and see if it makes a little bit of difference.

Raising the handlebar is a big possibility. Too bad the stem that comes in the Jamis (made by NVO components) is already at its maximum height. I think I'll replace with some other stem.