A big favourite is The Savoy Theatre, in London.
This is a really old theatre but they have done really well to make a Wheelchair Space in the Dress Circle. There is room for one wheelchair and a seat is put in for a companion, on a platform on a level with Row F of the Dress Circle.
There are a couple of seats you can transfer into if you are a wheelchair user and your wheelchair is then put out in the Dress Circle Foyer, but note that people will be hanging around it when going to the kiosk, as there is nowhere else it can go.
The Accessible Entrance for easy access is in Carting Lane. It is a 10 minute walk from the Box Office, due to the Theatre being built into a steep hill running down friom Strand towards the Victoria Embankment!
The 10 minute walk drops you down from the Top Level of the Theatre, (where the Box Office is (Strand Level) to the Dress Circle Level in Carting Lane and from there you go to the Stage Door and ask for the Access Host to let you in. You go straight into the Dress Circle, so you can normally only enter 30 minutes before the start of the show. It is easy to enter but on the way out you are going against most the rest of the audience leaving, so I would suggest leaving first or waiting until last.
Once in the theatre there is an Accessible Toilet and an Access Host normally helps with any drink etc. you need.
Overall, there is an excellent view, a good Accessible Toilet and an Access Host provided.
I would give this a 9/10 rating.