I need help choosing a style and size for bathroom vanity mirrors. I have tried to match the wood on the vanities but have had a hard time trying to find something that truly matches. So, what type of frame would work best in these areas? And how big should the vanity ideally be?

I have 3 bathrooms (all of which will have espresso wood cabinets with brushed nickel hardware).

1. Master bathroom (which will have 48" vanities on either side, left and right, as you walk into the bathroom, straight ahead is a white free-standing tub, corner right is a shower, corner left a room for the toilet; wall color is a soft, light blue- SW silvermist). The vanity tops are a cream-colored quartz.
2. Guest bathroom (one vanity, 33"; will have a shower with a frameless glass panel for the shower- no door)- color also SW silvermist. Vanity top is a cultured marble with very light gray/cream veining
3. Jack & jill bathroom (two vanities- two small rooms for each; ~41" each)- color in one is gray (SW dovetail), the other is a pale blue/green (SW contented). Vanity top for both are cultured marble with very light gray/cream veining

Thanks for your advice!