Leaving a six-inch space between the right side of the vanity and the wall would, indeed, be a waste of space, not to mention the fact that it would make it difficult to re-paint or paper that wall down the road.

Couple questions:

1. Is your shower staying within the same footprint?
2. What’s underneath this bathroom—i.e., do you have easy access to the plumbing lines? If so, in addition to reducing the size of the vanity, you might want to move the toilet over to the right six inches or so.
3. How long is that wall? Starting at the right wall moving left, if you allocate 36” for the vanity and another 30” - 36” (the more space you can spare the better!) for the toilet, how much space is left for the shower?

Here are some diagrams you might find helpful:

My old vanity was jammed in the corner as yours was. I replaced it with a vanity that's 4" from the wall (wide enough for a paint roller).

Here's what I'd do: On the right-hand side, measure 4-1/2" in from the stud.* On the left-hand side, measure 15" from the center of the toilet drain. That defines the maximum possible vanity width. Now round down from that number to a standard vanity size and install that vanity 4" from the right-hand drywall.

You may not need to fiddle with the pipes. Just choose a vanity whose with an open section (e.g., behind doors, not drawers) wide enough to leave pipes as they are accessible.

-- amateur

*1/2 is added for the thickness of the drywall

Sammy,

Yes the tub is staying within the same footprint. We'd prefer to not move toilet plumbing but slighting moving the vanity plumbing isn't an issue. The basement is just below this bathroom as we're in a ranch house. I'll comment back with measurements of that wall.