Is the vanity going to have two sinks? 90" is really wide for only two. What is the configuration of the vanity (doors/drawers)? What is the layout of the bathroom?

Only one sink as it is our guest bathroom. I thought about doing 2 sinks but I like the counter space and it is not necessary for our needs.
The toilet is to the right of the cabinets. Across from the cabinets is the tub/shower. The pic in the demo is from the bathroom door.

Sorry the pic is sideways.

plenty big for a guest bath mirror.

I think a 30” diameter mirror will look less dinky. It’s easy for you to do paper templates of both the mirror and the sconces in order to get all proportions and centering right. Getting the sconces centered vertically is important for a round mirror.

I would put 2 sinks and 2 mirrors in a guest bath. Why scrimp when you have the space to make it really great. When you sell, the more generous configuration will be a bonus.

I would NOT pair those rigid square sconces with that graceful mirror. Their design is too boxy and doesn't complement the mirror The scale of the sconces should be smaller when compared to the mirror scale.

You could consider the wavy frame in a rectangular mirror

28 x 44

https://meadowblu.com/products/regina-andrew-candice-mirror-rectangle

Larger Rectangular mirror 36 x 48

https://www.serenaandlily.com/products/wave-mirror/598889

Those mirrors are all wrong and IMO much larger simple no frame mirrors with bath bar lights are a lot better than those sconces will be but you could do those sideways instaed of vertical install above each mirror but not that mirror with those sconces ever Of course you provide no context like the vanity or the counter or the fixture color so working mostly in the dark. IMO those sconces are a great scale for that large vanity but if only one sink then how is that going to work Do 2 sinks 2 mirrors and those horizontal above each mirror and done .

I don't think 2 sinks are needed for a guest bath. If you have 2 guests they will both inevitably have their own toiletry supplies and need the room to spread out. But, getting the mirror / sconce pairings and scale right is critical. A paper template of all being considered will show you in person what Bev's mock up did.