Ben - Golden is a man made play park thats 1/4-1/2 mile long. Filter plant is a fairly flat section of class II on the Poudre.
The Poudre is starting to come in right now. Not sure what you are looking for, but all classes of whitewater are available on the poudre currently. The 12 mile stretch from Stevens Gulch to Bridges Take Out is Class III and the narrows above that has 3 sections a Class V section, a class IV section and a V- section at this flow (imo). The play is not great right now, but the river running is very fun. Check American Whitewater or Riverbrain or better yet buy a copy of Whitewater of the Southern Rockies for more beta on the sections.
If you head up the Poudre today and find the takeout for one of these sections you should find people to boat with. Especially after work.