I think its a great idea, and 3 would be perfect. Make sure they shine down on the countertop, not behind your head, where they would cast shadows.

Exactly what Jean said. I would use three 4" cans approximately 24" off the wall, this balances the light coming straight at you from the sconces.

if you're doing sconces, I would not do can lights at all. cans direct light down, casting ugly shadows on people's faces. vanity lighting that's near face level is much better.

Don't do the cans - agree - you end up looking like a horror show monster with all the harsh shadows. either sconces with good bulbs / dimmers / color adjusting or use an integrated LED mirror for better lighting. NO CANS

If you put them on separate switches you can do both. Are the sconces going to be attached to the towers or through, or on the sides, of the mirror?

Thanks for replying! Sconces attached to towers on separate switches. The sink area of the vanity is 8’ long so I feel like the sconces won’t be enough lighting? The ceiling is 9’.

Thanks everyone!

You have nothing to lose by putting small LED ceiling recessed lights on a separate switch. If you don't do it now, it will be a real PITA to do it later.

Separate switch and a dimmer. Small cans.