I'm afraid that this sort of thing makes buses only suitable for local travel, unless you've got bags of time or want to enjoy the view from the top deck, which is not a bad reason to go on a bus.

In my youth, I used to take the 176 from Camberwell to Oxford Circus as a daily commute. I'd get on about 8:15 and be at work just after nine and get lots of good reading time.

It's a similar dilemma train or fly. You wouldn't take the train to, say, Eastern Europe, unless you were doing it for the journey, on a very tight budget - e.g. gap year travel - or very green. But to destinations like Paris or Edinburgh, it becomes a much finer decision.