Using a slow flanger like the Deluxe Electric Mistress into a Roland Jazz Chorus amp with the Chorus switch on, is absolute bliss!
Running a H2O Liquid Chorus & Echo into an amp, with a stereo effects loop & Rockman Stereo Chorus/Delay to a stereo poweramp and stereo cab, used in the "Wide" setting (100% wet on side, 0% wet other side) is also very effective.
Using the Neunaber Chroma Chorus mono into an amp with the same stereo Rockman Chorus setup, is also very cool. That way you get just a slight bit of chorusing up front which works well for thickened dirt tones, and when you want that exaggerated wide 80s chorus lead swoosh you just kick on the Rockman!
At the moment I have the H2O in front of the amp (MarkIV), with both the Chroma and the Rockman in the effects loop. The Rockman splits the preamp signal to stereo as well as choruses when engaged. One output goes back to the amp and goes through its internal graphic EQ, to the poweramp, and 1 side of the 4x12 cab. The other output (un-EQ'ed) from the Rockman goes to the Chroma, which is always on. That output goes to an external poweramp, and the other side of the 4x12 cab. Running the un-EQ'ed and EQ'ed signals separately makes for a really good blend. The Chroma works really well to create a complex texture when used with dirt sounds (it almost sounds dry, not chorusey sick at all), which is helped along with the different EQ scheme, so it sits slightly under the EQ'ed signal. It also helps tame the chorusing sound of the Rockman, so when you want to sound like obvious chorused distortion but without sounding yuck, it works. And of course it makes the sound really wide & stereo which is great for clean stuff- nearly as good as the Jazz Chorus.
The H2O running (in front) with either the Chroma or the Rockman (in loop), sounds great for clean and mildly dirty stuff.
Also at the moment I brought my Marshall upstairs, and running it through the Jazz Chorus. And who knows....I might just run the Boss CE-3 in front of it with the amp's Chorus switch on...
I have done this.. sort of. Since I am using pedals for my dirt, I have at times run my TC Electronic SCF+ in front of the dirt, then run my MXR Stereo Chorus post dirt to split the signal in stereo between 2 amps. Some times you feel like a nut, sometimes you don't