For the last 20 years, we've had a good sized master bathroom 18'x8' with a 6' cabinet/counter top with 1 sink. I, nor my wife have never wished for another sink, and generally tend to use the facilities at different times for many reasons.

Who's using the bathroom?

We've recently remodeled our house. We have a single vanity for a bathroom that is used for one child's bedroom (and to be used as the bathroom for company), and a double vanity in a bathroom that is to be shared between two other kids' bedrooms (so they can brush their teeth at the same time, and have separate medicine cabinets). So I think your answer depends on who will be using the bathroom.

We have a double vanity in our master bathroom. Even if you and your wife don't mind sharing a sink, the average buyer of your house will value dual vanity far more than a single vanity for a master bath. (Watch those home buying shows on HGTV--the wife always oohs and aahs at the dual vanity in the master bath.)

Other thoughts:
Single vanity will allow more space. Either counter space if you're keeping the 72" length, or more floor space if you're going to shorten it to 60" or even less. Also less plumbing work, single vs dual, as that's the rough-in plumbing you've already got in your wall.

For our vanities, we looked at the big box stores and didn't like what they had. We looked at local bath places, but they didn't quite have what we wanted and usually are more expensive than online. In the end, we bought a couple vanities from Wayfair. They have been of good/decent quality. Most of the major online retailers (efaucets, Overstock, etc) seem to carry fairly similar stuff. We also bought one vanity off Signature Hardware. It is of slightly nicer quality (but also more expensive, and we had to buy faucets). No sales tax, which was worth a couple hundred bucks. We also thought of buying semi-custom cabinets and then finding a fabricator to cut a stone top, but that was more effort than we wanted to deal with (because then you have to figure out sinks and faucets, too).

This is the "hallway bathroom" in a typical CA ranch layout. The hallway leads to the generous size master bedroom (with a generous master bath). Along the hallway you have 2 small bedrooms and this bathroom. So, generally it would be for kids, probably for people with 2 kids. So, a future buyer or tenant may see use in having two sinks for their two kids.

Currently I lean towards 2 sinks. It looks like any vanity that's priced competitively (high volume) is 2 sinks. I also think it has a slight edge on resale. I also think my kids, while not using the bathroom together, will appreciate having their "own" sink. You know how much people like to share. That's why communism worked out so great.

It will be challenging to pick something contemporary that also ages well. Getting the latest fad (remember the wash basin sinks from 5 years ago?) will be a bad idea ...

G

If that's the only bathroom for the kid's bedrooms, then I can see two sinks, no question.

JR

Agree, sounds like a candidate for two sinks.

Kids bedrooms and guests, yes. Even a roommate situation would make 2 sinks a nice option to have. It is becoming more clear now ...

G

Your rationale for dual sinks is why we installed that in the bathroom the kids share.

For fads, I think current ones are having 2 smaller vanities in place of one larger one. So instead of a 72" dual sink vanity, install two 24" ones with space in between. And even if you go with a single larger vanity, having 2 medicine cabinets/mirrors (one over each sink) instead of one larger, full-width mirror is trendy. I can live with those trends, but I'm not a fan of the large stepped vanity--the two sinks have normal height countertops, but in between there is a lower countertop.

I also noticed that retailers only seem to sell vanities in three colors: white, some sort of light grey (whether it's grey paint or some sort of "grey oak"), and some sort of dark brown. It's a challenge to find a vanity NOT in one of those three color schemes.

I’d rather have two toilets than two sinks. I can always wait to brush my teeth. My only question would be should they be side by side facing the same way or facing opposite ways (so you can hold hands - so romantic) or back to back, or face to face.

Never had a enough room for a bathroom with a double sink, at first it seems like a good idea... I can shave while she brushes her teeth! But after some thoughts a second toilet is what I really want, which means a second bathroom.

A 6’ vanity with two bowls?

Not enough room.

IMHO.

Based on the additional info, two sinks for sure. Two of my kids share the hall bath adjacent to their upstairs bedrooms, fortunately it had two sinks when we bought the house. Why give your kids another thing to fight about?

You could consider buying a standard cabinet box and then having a countertop made for it. Assuming you don't like the retail options for countertops. We have onyx tops which we like, but there are a bunch of options for a solid surface countertop that are nice and not super pricey.

I think you have it nailed, and for kids, there can be times before church or school where two kids need to brush their teeth at once. There is no crime involved if there is a second sink, especially if there is a lot of room for a long vanity.

In your case it makes sense, starting with the layout. You are a smart guy, do what you think.

Very good point - "takes away storage...."
Also more plumbing machinery to take care of with a double.
.... and of course more cost.
I also like the idea of an outlet in a drawer to reduce clutter.

Now I look at my tub and it is a mess too. Starting to look like a total remodel :)

But 2 sinks it is!!!

Cast iron vs coated steel vs acrylic...

^^^ Haha!

Project on hold - total scope creep. If you do one bathroom, you should do both, so they are the same style. I don't want to work 6 weekends and spend 15k right now ...

G