I like eggshell finish; not too shiny.

thank you. I agree but will it look funny with the molding and bookcases in a semi gloss. was your trim also eggshell? It all looks great.

Keep your bookcases, molding, trim, etc. in the semi-gloss and the shiplap in the eggshell. Should be just enough of a difference to notice and the walls will look more say authentic?? If you're worried you could always buy a sample of the eggshell and one that's a bit flatter, paint them both next to your semi-gloss bookcases and see which you like better.

I prefer satin for trim work. It has a tiny bit more sheen than an eggshell (which I always use on walls), but is not as shiny as a semi. All of the trim in this house was done in Satin. I think you'll be okay combining the two sheens. The difference will be subtle, and I think semi-gloss is too shiny for a whole wall...unless you are going for a beachy "coastal" vibe, then I would do everything in semi-gloss.