The Spirit on the moon was awesome - Spirit was just silly enough, in general, to pull off a science fiction story in an otherwise earthbound series, and adding Wally Wood's art to Eisner's writing and art would raise it to that level even if there were more residual 'wtf'?
I'm not convinced Dick Tracy could pull it off nearly as well (two-way wrist radio notwithstanding)...at least not without seeing it.