For those of us who like default bridges (graphics), speed upgrades for default suspension bridges and the girder "pothole" bridge are in order.
Concrete: 80 -> 144kph.
Bronze - steel: 96 -> 160kph.
Golden - steel: 112 -> 224kph.
Girder pothole-cover bridge: 256 -> 448kph.
The biggest inspiration for this new .grf was the fact that NoCAB AI doesn't renew bridges with monorail bridges when available, but it includes many beautiful suspension bridges in its rail construction.
Besides - suspension bridges look so much nicer than those tubes - so why not make them more pleasant to travel on them!
EDIT: Let's include the source, shall we?