Dining Room Part Deux: Design Dilemma

Okay so heres my big problem:

We have a 3 bed, 2 bath house with one large living room and one large kitchen/dining room. Right now the arrangement goes largest/master bed/bath is mine and Adam's (obviously), middle bedroom (smallest) is the nursery,  last bedroom (middle sized) is the "office". I use the word office loosely. B/c "office" in my mind implies function. Where as that room is more like the pit-o-filth. And the pit-o-filth has a love/hate relationship w/ my dining room b/c they sort of feed each other. B/c the PoF no longer functions at all as a work space so when I need to craft/work/sort papers/etc I do it in the dining room (occasionally the living room, but the stuff gets stashed for the day out of reach of the kiddo in the dining room).

And many a time I have deep cleaned the dining room only to have it get funked right back up again in record time and I blame the PoF for the back log b/c things can't get processed through and filed/shredded/put away like they should. In my ideal, perfect world, there should be a place for everything and everything should be in its place and right now that JUST AIN'T HAPPENIN'.

So I'm having the realization that in order to tackle one I HAVE TO tackle the other.

And it seems reasonably easy. I should have PLENTY of room in my office to craft, store books (5 BIG bookcases FULL of books mind you) AND deal w/ my paperwork mess.

Here's the little monkey wrench tho: We want to have another baby in the next year or so. Theoretically we could put two kids in the same room. BUT right now the nursery is our SMALLEST bedroom and you'd better believe Mr Caleb and all his crap sucks up every last inch of it. So at the very least we'd need to try to cram our already packed to the gills office into the SMALLER of the two rooms, in order to have enough room for a bed, crib, 2 dressers, changing table, etc into one kids room.

The other problem with trying to put 2 kids in 1 room is that the baby will undoubtedly wake Caleb. That means crabby Caleb b/c he's been woken up repeatedly by his crying sibliling. NO thank you.

ALSO Caleb will turn 3 next year, that means he's going to start playing w/ all the toys that are for 3+ (aka contain choking hazards) so he's going to need his own play area where he can keep all his toys safely away from his younger sibiling.

So we need that 2nd bedroom. That means I've got to clear out my stuffed to the gills office and COMBINE it with my dining room (b/c theres no way in heck I can put all that stuff in my living room. Its FULL). My single scariest thought right this second is: where the HECK am I gonna fit my (absolutely essential) filing cabinet!

GAH.

The first thought I'm having is that the bookcases are going to get doors and get moved into the dining room. Like do a whole wall with them maybe? But ours are the Billy bookcases from Ikea in the brown black. Yeah I didn't pick that color. Adam had 2 of them when we got married so when we bought more we just bought them to match. So a whole wall of DARK book cases sounds very oppressive. I mean I might be able to pull it off like we did in the office by sticking w/ this pretty robin's egg blue on the walls and white trim but I'm not sure I want it in my dining room... I could theoretically paint them all white and just buy white doors for them but MAN that would be a pain in the TUSH.

Maybe I could replace my filing cabinet w/ one of those Effektiv systems from Ikea... Of course that would mean parting w/ my perfectly good, only a couple years old filing cabinet... *sigh*

I dunno. But I think this TOTAL revamp is going to be the ultimate answer. *SUCK*

Oh and if the office becomes Caleb's bedroom I just have one question: where the heck are the litter boxes gonna go???