Orion and Jupiter have the Planetarium dome. There are, I understand, no plans to add on any future builds.
I know lots of people think they are a waste of time and space but if utilised in the right way by Viking it can be a real treat. On Southern Atlantic Crossing last month the resident astronomer was fantastic. His Theatre talks, on deck stargazing and yes, Planetarium sessions were a highlight of my cruise. The other dome shows were worth the time as well. The resulting loss of sitting space is hardly a problem given the multitude of quiet areas on all Viking ships.