If you don't plan on selling, do whatever you like. For resale, don't get rid of your walk-in. If anything, I'd be stealing a couple feet from the master bedroom and making both the closet and bath bigger. eg a 10x12 bath, 10x6 closet and 15x18 bedrooom.

I measure closets by the amount of stuff you can actually store, and not by whether or not they are called walk-in. Some walk-ins waste storage space. I do not have a problem with standing in the actual room to get my clothing out of the closet. Do people go into the walk in and close the door? Is the floor space used? If not, I would go with the wall of closets if it had more storage space than the walk-in.

I'd go for the bigger bath, too.

Space that "does something" like a bathroom or closets, is really necessary. Space that just makes things bigger, like more square footage in a bedroom, is nice, but it seems wrong when the supporting spaces are too small.

Plus, the wall of cabinets provides an opportunity for enhancement with decorative woodwork.

I vote for a long wall of reach-in closets. They really are more functional than a walk-in. So many walk in closets are narrow, too narrow to walk in with a laundry basket on your hip. A wall of built in wardrobes can include some drawer space and eliminate the need for bureaus, making the bedroom feel much larger.

But I am biased, walk in closets always have made me apprehensive (I swear I'm not claustrophobic, I've been in deep caves, but I just don't like walking into a closet).

Exactly what jamies said. I have a small walk in and would be just as happy with the same amount of storage in the form of closets along a wall. I never really leverage the "walk in" feature of the closet because it's too small to make it really usable in that way. Certainly a massive walk in closet with room for seating, mirror, etc would be a lovely dream, but I'm more interested in maximized storage and functional usable space. As long as the new closet space is well organized and looks like it belongs in a master bedroom (go for nice doors rather than basic bifolds, etc), I think it's a smart plan.

I can't find pictures of the episode, but in one of HGTV's Sarah's House seasons, Sarah Richardson designs a really beautiful bedroom with a wall of reach in closets near a dresser where it creates kind of a "dressing space" in the bedroom itself. It's really beautiful and the storage looks much better than what you'd find with a walk in closet.

Pricklypearcactus, was it something like this one from ikea?

Here is a link that might be useful: small bedroom walk in closet from wardrobes

Thanks everyone so much for the guidance! I am completely fine giving up the master closet for a great master bath. I am definitely planning on making the wall of closets very high end looking!

We were having this same debate. We would use the entire "walk in" closet for a new master bath. We have none now. Sadly we do not have the room footage you do so putting in the wall of closets would encroach on the room too much. "Wanna be" walk in closets are the worst. Unless you really have the footage to make a true room size walk in closet I do not see the point, for the reasons already stated. The only way this could negatively effect your resale value is if you have prospective buyers who can't think for themselves and are totally duped by the likes of HGTV offerings. As long as there is sufficient storage you will be fine. The closets prickly.... speaks of was in the older home she did for "Sarah's house". Canadian sentiments may be different than ours. Sarah has no need for an en-suit bathroom or walk in closet. Frankly I have no problem dressing in my bedroom. I have no desire to dress in a closet or a bathroom.

A 6x18 bath seems long and narrow, and I'm not sure it's the best configuration for the square footage. Can you post your floorplan so we can see the relationship between the bedroom, bathroom and closet? Perhaps a different configuration would make the whole space more usable.