Paint is the obvious solution to the wood not matching on the front. But, the back and side splash actually looks strange / dated now that you mention it. If you can find a way to avoid that completely, I would. For example:

Don't leave it open, it will always look unfinished. Use wood to go down the sides and paint the wood to match the walls. Nobody will notice and it will look great

I would go with a free standing vanity.

Yeah.......... a fun place to clean at the sides.......: (

IMO by the time you fiddle around with adding stuff you could get a customvanity.

thank you everyone for your thoughtful comments. I guess I have to agree...it would be MUCH better to do the whole thing custom. But that will more than double my costs and bite into my budget for the project....the wet room will be very labor intensive. But I am going back to the drawing board to see if I make that happen, because I know it would look waaaaay better.

You do not need full custom cabinets here. You can use stock sized cabinets with 2 1 1/2” fillers on each side. A 60” double vanity cabinet could be found in a many budget lines for $600-$700 if you didn’t do a lot of drawers, or an ornate door. Oak is the least expensive wood, then birch, then thermofoil, then maple.

There are lots more choices though if you are willing to increase the budget a bit.

@The Cook's Kitchen.... well that is exactly what i have been trying to do. I found exactly what i want....a prefab vanity set, that includes countertop, sinks and mirror for $1538....but can't match the wood for the fillers. I could get that same thing for $1369 or $1493 in finishes that are not my favorite....and might be easier to match. But a stock cabinet will also require those custom marble sidesplashes. Others on here thought that solution would look tacky. And be a big hassle. So I'm researching the custom options. This whole bathroom remodel is turning out to be a whole lot more difficult than the total remodel of my kitchen i did a couple years ago with a lot of help from Houzz.

A custom 63” top isn’t a big deal. Just go to a stone fabricator who has remnants. $700-$1500, depending on color. Including sinks and install.

A Kitchen and Bath Designer could help you with all of your decisions. Including good sources for materials and pulling everything together. If you work with one who would sell you the cabinets, you likely would not pay any more for the service than you would just buying the cabinets. Most fold their fees into the product sales. You end up with a better project, for less money than making a few mistakes all on your own. Talk to a couple of designers local to you.

Thanks, @the cooks kitchen.....good idea. I will investigate.

@Angel 18432 how many inches is your freestanding vanity from your walls on both sides? thanks!

@akmcmullen That vanity is just a suggestion, not my personal bathroom.