The 77W and a connection on BA will take you to Europe just fine, to Paris or somewhere else.
CX or JAL will give you a nice trip to Tokyo, I would probably go with JAL.
Paris is the most visited city in the world, but yet it remains rather unwelcoming to foreigners, its attractions often overcrowded, its public services prone to random shutdowns (by strikes), its waiters famously hostile, etc. Go if you like, but I've never quite seen the loss-of-rational-thought level of attraction it holds to some people.
Tokyo is fascinating, complex, and fairly easy to get around as a foreigner; many places are well set up for tourism, and even things which are not, tend to have a formulaic way of operating so if you just go with how things seem to work and be polite, it works fine. Most Japanese things are set up to operate in a particular way (restaurant service, visitor attractions, train boarding, etc) and if you go with the programme it works fine. If you try to go against the programme, it gets hard, so go with the flow. Tokyo is very safe; certainly safer than San Francisco. Japanese people are nearly always dedicated at their job, so if their job is helping you then they help you well, and often very helpful even outside that.
Both the US Dollar to Euro and US Dollar to Yen exchange rates are in your favour at the moment, making either feel cheaper than it would have done a few years ago.