I recently have acquired some new effect units (Eventide Space, Strymon Timeline) that I have been experimenting with different setups, and I have recently come to a pretty neat one.
Originally I had routed both effects to the AUX of my mixer (mackie 1620i, for those who care,) primarily so that I could have the maximum depth of application. This way dry and wet are parallel, and could mix everything to taste without too much signal loss/noise/digital artifacts, as well as stretch the effects over 16 tracks rather than just 2 outputs.
However, upon recording simultaneously to tape as well as DAW, I soon discovered that on this mixer AUX -> FW does not work, therefore only the tape was getting any of the effects, while the digital version remains dry (appropriate in some situations, of course.) So after some trial and error, instead of having the AUX outputs go to the AUX return of the mixer, I started to input them into the mixers actual channel strips. This was actually better in many ways because now I also had 4x more stereo EQ and panning to shape the incoming effects, as well as the best part about this routing: the AUX effect feedback loop.
Adjusting the AUX mix on any of the effects (on their returned channel strips) creates a reciprocal feedback loop, which, at more intense settings will clearly feedback into oblivion, but on lighter settings (less than 50%) you get: dry signal(s), wet signal A, wet signal B, where A & B are both feeding into each other. I thought this was noteworthy, and will certainly have some interesting applications.
NOTE: This only works if your effects units MIX are less than 100%.