A double vanity with two vessel sinks (as seen here in this bathroom ... In this bathroom from @abbey__singharath, the walls, ...

Length is limited only by the size of the countertop and the design of the vanity. Below are the ... Because they sit on top of the counter, vessel sinks can have wider openings than top-mounts ...

and vessel sinks, which sit on top of the counter, with any countertop material. Just be sure overall height of the vanity plus the vessel sink isn't too high. Under-mount sinks require waterproof ...