Voyager 2 was the real beneficiary of the rare outer planet alignment, as it went on the famous Grand Tour, visiting all four of the giants. It did gravity assists at Jupiter, Saturn, and Uranus. [1] shows the rough velocity of V2 over time.
Voyager 1 was directed to perform a flyby of Titan, at the cost of being thrown out of the ecliptic and being unable to visit the ice giants like its sister. But this was deemed acceptable due to Titan's high science value.
[1] https://commons.wikimedia.org/wiki/File:Voyager_2_-_velocity...
There isn’t much value in gravity assists from Uranus or Neptune since they move much more slowly than Jupiter and Saturn.
To save someone two seconds of searching,
NASA animation of Voyager 2's trajectory (time in the bottom-left corner): https://youtu.be/l8TA7BU2Bvo