Our MB is 4.5 x 7' I think. Our vanity is 24" wide. I use the MB, DH uses the hall bathroom, so I only have to store my stuff in the MB (extras, overflow, towels, etc. are stored in the linen closet in the hall bath). A few things that helped; 36" tall vanity (incl sinktop) with drawers in addition to open space, allow me to store a lot. Also, we installed a 6" deep recessed medicine cabinet (the add'l 3-4" bump out into the closet behind the bathroom wall). I can fit a lot in there! They make an 8" deep version as well, but I didn't need one that deep.

Our vanity is against a wall, and we hung the medicine cabinet so the door opens towards that wall. I'm pretty sure that was why we chose the 19+" medicine cabinet instead of the 24" wide model. We could have gotten the 24" wide, but the door would not have opened as far as it does now. I like begin able to open it as far as I can, as the Robern medicine cabinet doors are mirrored on the inside as well as the outside.

HTH!

I've gotten used to hiding my waste basket under the sink because we've had dogs for so long. So I would never give up 6" of vanity space to allow for a waste basket - but that's just me! If you opt to keep a 36" vanity, you could perhaps find a smaller waste basket to fit way back in the corner between toilet and vanity.

Someone on this forum posted long ago about using a recessed waste receptacle mounted in the wall, like you might see in a public restroom. That made me think it would be possible to do soemthing like put a little flap-type door in the side of a vanity, with a trash receptacle inside the vanity. Something to consider, perhaps?

I like that recessed trash can idea kmcg. I started keeping my trash can under the sink when my DD started crawling. It looks much better to me now especially since I didn't really keep anything under the sink anyway except a couple of cleaning supplies and the necessary 'toilet' stuff.

I found a very small wall mounted trash can on Amazon that is normally used in an RV. But it looks like it will work for us. Take a look:

I haven't bought it yet so can't tell you how it works. There are a couple of reviews that don't sound too bad.

Here is a link that might be useful: Small wall mounted trash can on Amazon

Hmm, OP... my two full baths are roughly those dimensions and I believe the 36" vanities the builders put in are probably considered "standard." Our vanities are "solid" (without legs like a furniture-style would usually have) and I do agree that the rooms would look less cramped with smaller vanities or at least less "solid" vanities. Ideally we could get rid of the vanities and have pedestal sinks, but we need the storage space and counter space.

At first I thought your bathroom was configured exactly like my bathrooms, but I just measured and mine are actually a little bit more than 5' deep (though 8' wide, like yours.) With the 36" vanities we do have room for trash between the vanity and toilet, but it's just a tiny little round bathroom trash can, not anything with a cover. I think, though, that if the rooms were exactly 5' deep, we would have to tuck the trash can sort of in behind the toilet, or place it behind closed doors in the vanity.

A 30" vanity is really pretty small, though... I just measured to see just how much smaller my counter space would be if I lost 6", and I think it would just be too small. I wouldn't worry so much about loss of storage space underneath, but rather about not having a comfortable-sized counter space on top, for splashing water around when I wash my face, laying out my hair dryer/products while I'm getting ready, etc.. We also have recessed medicine cabinets on the walls beside the vanities, which is helpful for storage of small stuff.

If you're more worried about loss of storage space underneath, than counter space, have you explored "mining" any other spaces for storage space? Sometimes the wall next to the shower/tub (the space in which the pipes reside) is wide enough that you can take advantage of the hollow space behind it, creating recessed shelves or even a small closet with a door.

One last thing to consider is what kind of mirror you want. (For some reason I assume your medicine cabinet will not be used as the mirror above the sink, but I might be wrong.) We have a nice big 36" mirror. I temporarily tried a smaller mirror but didn't like it. If you go with the 30" vanity, I think you might be limited to a relatively small mirror. It could look odd to have a mirror which is wider than the vanity, so you'd likely stick to 30" or smaller, which you might find too small.

I too like the idea of a recessed trash, but that could look a little institutional perhaps. I vote for larger vanity, trash under the sink. Or a custom vanity that utilizes every inch you have.

My daughter's bath is small and I took the vanity from wall to kneewall (it would have resulted in wasted space anyway). The wastebasket just floats in front of an open shelf (which in retrospect could have been drawers, they would not hit the toilet).

I'm currently trying to figure out the best layout for a 5x8 ensuite in our new build. I've come up with several possibilites but none of them seem quite right. If any of you could share your layout I'd appreciate the help. Thanks.

My pet peeve with smaller vanities are that they severely lack drawer space. If it's a hall powderroom, you can get away with just having doors instead of drawers, but if this was a bathroom that is a master or directly for a secondary bedroom, then to me, it's vital to have drawers. Where else do you put your stuff...comb, brush, small makeup items, etc? Yes, you can put that stuff in multiple bins under the cabinet, but then you're stuffing bins of stuff that you use everyday under the vanity. Drawers are far more convenient. It wasn't until we stepped up to the 36" size that we began to see variety of vanities with a good amount of useable space in drawers.