The extra 4" would allow room to hang a robe or your everyday sweater on the side, or to more easily reach the items on the far ends of the hanging rod, and to access items on the top shelf. I just was in my 24"-deep reach-in and would appreciate a few more inches.

My husband's formal clothing (sports jackets, nice shirts, etc., for Mass) is squished in 24", and he's built like a basketball player (tall & thin). I would go for 28".

[Actually, I would go for 30", lol, but I'd take 28" over 24" any day.]

28" will reduce the possibility of sleeves getting caught in the door.

thanks everyone for your responses! I am surprised its so unanimous. Sounds like 28” is the way to go. Thanks

Make sure to locate the centerline of the rod 12"-14" from the back wall.

A 24" deep closet is approximately 27"deep at the doors so the answer to your question depends on the width of the doors. If they are 90% the closet width then the additional 4" of depth would be better used in the room. If the doors are 50 % of the closet width, a 28" depth would make it easier to get the the clothes at either side.

There are few, if any, useful rules-of-thumb in architectural design.

If the doors are framed and don't cover the entire space, then the space that overlaps on each side that is 24" will not accommodate hangars. 25" is the bare minimum to hang a hangar and close or slide the door closed.

The width of hangers varies from 16" to 19". The width of a 42 L suit coat is 20" at the shoulders and 23" at the elbows. If the hanging rod is 12" from the back wall, the coat will fit in a 24" deep closet beyond the door and at the door it will have an additional 3" to spare at the front. A front hall closet should be 2" deeper to accommodate overcoats and ski parkas. If the space beyond the door is more than a foot, an additional 2" would be helpful.

I just measured 2 of my husband's 40R sports coats (he's tall, but it's all in his legs lol). One is a J Crew, one is a Bonobos (so, trimmer/thinner cut brands). Both jackets, at their widest points (which is actually cuff-to-cuff on a hanger, because the sleeves flare out a bit from the shoulders), measure 24".

So, 28" would give us 2" on either side of his jackets for air flow and clearance from doors if we had a reach-in closet. :-) (We had a 24" reach-in closet in the rental, and his sport coats' sleeves were always getting smooshed.)