The Bibliophile's Dilemma

As we make plans for our living room redo, one of the issues we're pondering is whether we should hire a carpenter to create some custom built-ins for our ever-expanding book and knick-knack collections.  Is it more economical to invest in substantial, well-made pieces that we can take with us to our next home or in built-ins that, as fixtures, would stay with our current house and (hopefully) elevate its property value?

Domino via Patricia Gray

Like Borges, I have always thought that paradise would be in the form of a library.

Martha Stewart

And what kind of bibliophile would I be if I didn't dream of floor-to-ceiling bookshelves like these?  And with a ladder!  Swoon.

Sköna hem via Desire to Inspire

I particularly love the fact that the built-ins in these photos all feature shelving around big cut-outs, for the door in the first photo, the display shelf in the second, and -- genius -- for the mirror in the third.

Since we have a cathedral, sloping ceiling in our living room, customizing built-ins around the portal from the living room to the dining room would be a great way to maximize storage space.

My only qualms about the built-ins idea (expenses aside) is that there's something very appealing to me about the fact that the room as it stands has such clean lines: it's a perfect rectangle, totally minimal in a mid-century way, but still open to all decorating possibilities.

What are your feelings about built-ins?  Worthwhile investment?