I was a member of the UK Club (the oldest in the world by the way) when I lived in London and had some great events, both big and small. The International Event is generally very well organised though quite pricey.
I hear that the official celebrations may end up being split as follows (no official news yet): the Maserati International held in September by the Maserati Club Italia and a invitations only event organised directly by Maserati for a few owners.
As far as I know Club Tridente in Spain is no more.
The chap who is setting up the club in Spain is based in Barcelona. He doesn't speak English though.