I'm surprised your TA suggested the Taj in London. I would never and Victoria is an odd location IMO. I love the Connaught. The Beaumont is also great and they look after guests very well.
Crillon or Ritz would be right in Paris. You could also look at La Reserve, the hotel bar may not have much of a vibe - a bit more residential here. For something different, I like Hotel Lutetia - it would tick all your boxes (the bar is amazing) if you were open to the Left Bank. I had a client say it was one of his favorite hotel stays ever. I don't love the Golden Triangle as a location, so that would rule out Plaza Athenee for me.