I guess it depends on whether you want a complement or a contrast ;)

If you want a complement, to me it has a distinct Arts & Crafts feeling (a bit less severe than the most traditional old-style fonts, a bit more rounded), a bit like something Goudy might have done. So would Goudy Sans work? That's calligraphic and humanist, but in an eccentric way. The italic would show it off at its best.

I guess the alternative would be if you want a contrast a typeface that looks good in bold so it really stands out against the serif font. Perhaps an old grotesque font with a bit of irregularity might be nice - maybe something out of Stephen Coles' list. Monotype Gothic Bold Extended, say (caution: spacing is a bit off). Or Alegreya Sans, though that's more calligraphic again.