We had several Archers (6 undermount plus 1 pedestal) in our last house and like them so much we are also putting them in all the bathrooms again in our new build. I like the edge detail and its not hard to keep clean, no splashing....

I would definitely go with the 20.5 I purchased the small ones (on backorder right now) for the master which will have a 72" wide vanity and two vessels, but want a light (or two) between the cabinets. In the guest bath, I'm eyeing a 24" and wouldn't consider anything that is wider. It might look ok, not sure, I haven't seen it done tbh. I think you could definitely install an electrical outlet inside a pre-made medicine cabinet. We did so in one of our kitchen cabinets. GL!

Cat_mom and phylhl, thank you so much for sharing your experience. Did you get your Robern cabinets at local stores or online? I saw Amazon has very good price on Robern sold by Faucets and More. I don't know if it's good to order from there. I am now buying materials first, then I'll interview contractors to do the remodeling. Really appreciate your help.

Did you pick a sink yet? I got a kohler impressions(?) sink for my 24" vanity. It's integrated white cast iron. It has a surprising amount of counter space for a 24" vanity top. Nice cute circular sink depression. You can't store anything on it permanently except a soap dispenser, but there is enough room for the little plastic basket I got at bed bath and beyond. Otherwise you can put the plastic basket on the toilet seat. I put a washcloth down to keep from scratching the toilet seat. Mine is painted wood and it does not like water splashed on it either. Make sure your vanity will support the weight of your countertop/sink.