Originally Posted by
Aviatrix
If you're a tourist visiting both Paris and London Eurostar wins hands down - town centre to town centre it's much quicker than flying.
What he said. As an American, doing it flying once -- and dealing with short haul European service which is nothing to write home about (pretty much what US domestic was before the budget cuts of the past decade)-- was quite enough.
From the parts of London of interest to tourists, to the parts of Paris of interest to tourists, avoiding the trips to and from the airports (especially with the annoyance of bags on the RER) is a huge plus, as is avoiding Heathrow Security and CDG in general.