Some, but not all, of the Telarc Spacializer CD's make mention of playing the discs back in both Dolby Surround and Circle Surround, right around the same area where the Spatialzier is mentioned in the "technical" section of the insert. So at the time in the late 90's, those would have been the recommended playback decoders. A Shure Acra-Vector decoder probably would do well also.
For modern day playback? I'd suggest giving them a spin with Dolby Prologic II or DTS decoding. Fredblue (and others) discuss these Telarc Spatializer disc
this thread also. If you've got an older SQ or QS decoder it would be interesting to compare, and maybe note for each album, which decoding method sounded best for you, that way you know what to use the next time you play it.
Both of the threads cited got me going on looking out for these Spatializer discs, just as another one tipped me off to Dolby Surround discs. And with Muldaur, she's even got a third Telarc Spatializer CD: "Meet Me Where They Play the Blues" Telarc CD-83460. I was on a recent deep trawl for surround discs, and there it was staring me in the face, where I had already picked out "Southlands of the Heart" and didn't notice it. These sort of surprises really put me in a heightened awareness when I see Telarc, Chesky, BMG/RCA/Victor, etc. on the spines of CD's!