You may have already thought of 'Rotis' and 'TheMix' / 'Thesis'.? ( The 'standard', classic suggestions for 'Semi Serif'.. :)

What about 'Keule', by Hubert Jocham, or, 'Sovereign', by Nick Cooke.?

Dav

I am really liking Storm's Areplos.

ChrisL

Funny, I ususally recommend Storm faces, but today MyFonts' font of the day fits the bill: Cicero by Présence Typo. I was checking out their library, and IMO it's right up there in quality with Storm. Great stuff!
I think Laricio also fits in your semi-serif search.

FF Avance by Evert Bloemsma.