Next step in grnd floor Reno? Design and builder? GC? Architecht?

We are planning to install a new bath in center of our ground floor (will need plans filed I assume),
demo the old crappy one
Renovate the back of the floor for Master bedroom including closets adjacent to the bath.

We have a very good idea of the design we want but are interested in hearing expert ideas.
Also have no GC’s in mind yet. Since it’s our only bathroom and we will be living with my mother during the dirty times (!) we want it done well, but QUICKLY too. We can’t stall out for 6 weeks while looking for the perfect vanity to restore.

Should we use someone to design and build, or find a GC with good ideas too?

Also what are your favorite showrooms for bath?