If there is a gap International Residential Code requires 4 inches so you can reach in to clean or retrieve something if it falls there.

Have you tried Houzz.com? I guarantee you'll find lots of vanities that will please your eyes. I would use the whole space so you get the most in drawer and counter space.

I'm planning a wall to wall vanity in my tiny powder room .

I only have less than 38 inches to work with, so I'm going with a built in look.

I do agree if I had 65 inches, I'd consider a gap on either side because I like the furniture look, but that limits you to 57 inches, so you have room to pick up that pesty eyeliner pencil that decides to roll off the edge. You have to decide if the extra counter space is more important.

Form vs Function

Always ;-)
Hunzi

Don't do a gap! The vanity we have in our jack and Jill bath has like a 2"gap and its awful! You can't paint in there and it's possible but very difficult to fish something out from there. We did have wall paper and when we went to have it removed we couldn't get it all off! Short of removing the vanity, there was no good way to do it. Either get a custom vanity or have the walls studded where the vanity will touch the walls.

This is a 54 inch custom vanity between 2 walls. It's important to order the cabinet with extra long stiles on both sides, so they can be scribed to fit the wall. When it's done correctly, there is no gap between the wall and the cabinet.

Another vote for no gap. Go wall-to-wall. Gaps create problems with water dripping down, items falling down. If you want a medicine can on one side the gap looks weird. Space is one thing but gaps are another. I put two furniture-style vanities in my previous home and did the gaps, but I wish I had not.

We have 3 vanities between walls in our home- all with no gaps. Unless it is a furniture style vanity, I would do no gaps.

Thank you all for assure me that no gap is the way to go. Function is more impotent for me, cannot image me bending over pick up some thing between gaps . I definitely will check out Houzz for pictures. Love this site,