St Pancras is "quite nice"?!

It's a wonderful building, both inside and out. I think it's one of the most beautiful buildings in Europe. Neo-gothic and wrought iron.

Image search: https://www.google.co.uk/search?q=st+pancras+international&t...

There could be more seating but it's pretty spectacular otherwise.

St Pancras is a beautiful piece of architecture, and has some nice shops, but the pattern of circulation was completely wrecked during the redevelopment, perhaps to encourage people to visit said shops. Happily, the one trip that isn't a massive pain is getting to and from the Eurostar terminal. Security is pretty quick to get through, but there's nothing much on the far side, so leave it until the last minute, and enjoy the station, or even better, if riskier,

Gare du Nord is architecturally pretty average for Paris, ie beautiful, at least from the outside. The shopping is disappointing: the best bakery for a last-thing-you-eat-in-France snack is a Paul, of which there are dozens in London anyway. Security is again pretty quick, and past it there are some comfortable enough chairs, and some overpriced and fairly useless shops.

The atmosphere inside St Pancras is better than inside Gare do Nord - it's brighter and arier. That's pretty much the only difference, though.

The Gare du Nord Eurostar terminal has been revamped in the last few years - it's much better than it used to be.

That's kind of scary, actually, given that my impression of Gare du Nord comes from only a couple months ago.

It looks a lot better from the outside than it actually is on the inside.