The household would probably have more usable storage with one big closet, but I think there would be far fewer disagreements and better opportunities for maintaining order with two separate closets. That would go double for a situation where the kids or whoever is in the adjacent rooms are not same-sex.

I think for kids, the walk in closets are preferable. I just think having that 6X6 area they can each enter and be surrounded by shelves and/or cubbies and then exit and close the door is nice. Plus you can have regular passage doors that open and close easily. Depending on the age of the kids, I find long bifolds or sliding doors for reach in closets to be ackward for them.

I definately prefer the 6x6 closet for kids. Our kids bedrooms have closets about this size and I like that combination of shelving and hanging space, plus the additional benefit of being able to pitch "stuff" in on the closet floor and pull the door closed in case of an emergency visitor. The other advantage in my mind is that you don't have so much wall space in the room devoted to the double or bifold doors. In our guest room, we did end up with a reach in closet, which also provides a lot of storage, but some how, the boys closets just feel "better" to me. Here are a couple of pics.

Small walk in closet

Extra "toy" closet

Reach in closet

Walk In. Another advantage is that for walk in you need a single door. For reach in you will need double doors (they get too much space) or big folding doors.
I think walk in has also better resale value.

Another vote for walk-in closets here. Both of my boys (17 and 14) have walk-in closets in our new house and we love them. Band instruments, football shoulder pads, backpacking back packs (great place to keep them out of sight during the week or two it seems to take to pack them for a trip, tennis racquets, etc.), all fit easily in the closets. Also, if you can get them to dress in the closet, then the cloths that inevitably get left on the floor when they change end up on the closet floor instead of in the middle of the room.

Walk-in closets should leave you with more useable bedroom wall space. As has been said, each one has only a single door, and you don't need dressers in the room to hold clothing.

Walk in closets use more floor space than reach in closets. For a given amount of floor space, they store less than a reach in closet. That is because the "walk around space" in a walk in closet cannot be used for storage, while the space taken up by a reach in closet is all storage space.

If you make a walk in closet so tight that someone has to squeeze in it to use it, it will become old in a hurry. The minimum inside wall to wall width of a walk in is seven feet. Anything less won't work, unless you don't intend to have hanger space on both sides. In which case, the human space in the closet is even more wasteful.

BTW, I love walk ins, except for the one we have now, which only has hanger space on one side. Even so, I realize that they are an inefficient use of floor space.

Agree with frog-hopper, except that I don't like walk-ins at all, ever. (Yes, I've lived with them both in the roomy version and the skinny versions. Bah!)

A well designed reach-in closet --even for kids-- should be no more 2'6" deep, and reality is that 2' is plenty deep. Rods should be hung according to height of the clothing rather than some cloud-in-the-sky guess. Rod-over-rod is very efficient for kids heights 4'+. Put pants and skirts on the lower rod, coats and shirts on the rod above.

Spend a little money on buying transparent stackable shoe-box drawers and 'sweater' drawers which will give you 100% usable space. These boxes are nearly unbreakable and will provide years of convenience. Use one side of the reach-in closet to stack the boxes, and forget about having separate bureaus! It is very easy for children and adults to locate the clothing that can be seen rather than having to dig through deep dresser drawers. Amazing how self-help improves.

Do design the closet so that it is accessible all the way to the ceiling. The common almost-hidden shelf over a rod is needlessly awkward, and usually wastes a great deal of space. You should be able to reach every corner of the closet, top and bottom, *easily*. Either have tall doors or design so that the portion closest to the ceiling has its own doors.

Folding doors are the most convenient, and sliding doors are the least convenient.

I fought hard for our walk in closets (one giant one in our bedroom and smaller ones in the kids rooms). However, I'm not that thrilled with the end result. The reach in closet seems like it would have made more sense. I think one problem people have with the reach in is that those bi-fold doors tend to look tired after awhile. However, you can put regular doors on a reach in closet. Just make sure the plans indicate that so the drywallers leave space for it. Or, a better option, I think is a wall of built in storage. Probably an expensive option but one I would have loved to have.

Regarding our walk in closets... I wish we would have used pocket doors and asked for a motion light in the big one. I'm always leaving that light on.

Carolyn ~ Good point about heavy jackets and coats needing extra depth. I completely forgot about that because I have never used BR closets for coats! I don't know anyone who does -- coats are always kept in the closet by the outside door, bymmv. And yes, the coat closet is 34" deep.

In my room with 12' closet, a) multiple bi-fold doors were used, they only take 1' foot of space when open and b) the area in front of the doors is walkway beside the bed. Walkway is needed whether or not the floor space doubles as standing-access area for the closet. One thing I learned (and it's hard to believe until you've lived with it a while) is that if you store all your clothes in the closet, you don't need the usual extra space alloted for dressers/bureaus because you don't need the dressers/bureaus!

Multiple small drawers stacked up and used instead of shelves actually provide more usable area because stacks of folded clothing don't fall over, and you don't have to lift anything to reach the item on the bottom of the stack. Apparel stays clean and neat because each drawer holds only one item, or in the case of socks or undies, a limited number of items placed front to back in the drawer which are each easy to reach. Also, nothing ever gets lost at the back of the shelf because the whole drawer is visible and easy to access front to back. Okay, I probably sound like a salesman, but I'm not, it's just that I'm so impressed with how much easier life has been since I switched over to using those neat drawer-boxes. The next time you have to dig something from the bottom of a dresser drawer, think about how much nicer it would have been to just reach for it without having to dig.