If I remember rightly, the rides at Gardaland that have the turnstyle countdown queues are:
Space Vertigo
Fuga d'Atlantide
Blue Tornado
Magic Mountain
Flying Island
4-D Adventure
The queues for Fuga, Blue Tornado, Magic Mountain, Flying Island and the Rapids all move pretty quickly. Space Vertigo's doesn't - if it reaches out beyond the zig-zag of hedges which is near the front of the queue, avoid it till it goes down. But at night, this shouldn't be an issue.
Colorado Boat's queue can get huge, but it looks a lot worse than what it is. Ed & I only ended up queuing 1/2 hour for the ride despite the line being nearly full.
Also, the front of the park has a beautiful carousel with two levels - worth a Kodak moment or two!