There really isn't a recommended size. Much of your choice will depend on personal taste. Personally, I wouldn't go any larger than 22" wide, as I rather have considerable real estate on my countertop. Also, you need to take into account whether you are using two medicine cabs above each sink, two mirrors, or just one large mirror.

I have a 96" wide countertop with two 17" oval Toto sinks. The reason for this size was that I was putting up two 19.5" wide Robern Candre medicine cabs with the matching wall sconces. This way I had the sconces mounted at the ends of the 96" countertops and the cabs centered above each sink. Then the third and fourth sconces were placed on the other side of each mirror. I found that the sconces looked best when their tops were 4" below the tops of the medicine cabs. I made sure I had at least 6" of countertop left on the margin of each sink to accommodate the sconces so they wouldn't be past the 96" mark on either side of the countertop.

Basically, what I'm trying to say is that you need to plan ahead on what you will be putting on the wall above the vanity before you decide on the sink size and how much countertop you want on the "short" side of each sink. You don't want to run out of countertop space if you are putting sconces up or other side lighting. Though with 100" of countertop, you do have a lot of real estate to play with.

Greg

I have two larger sinks in my bath and the problem that I ran into was not width of the sinks but the size from front to back. By the time that the faucets were put in--they have an oversized base--they look jammed between the sink and the backsplash. I will never do that again and wish that my designer would have picked up on this. I just figured that a bigger sink was better.

how deep is your vanity? She thinks we can get a large sink and the vanity is 21in. deep.