It would have been interesting to see what would have happened if any of these ventures had been successful. I don't know whether SPARC chips make better laptop processors than PowerPCs, but if they do, then perhaps we wouldn't be seeing Apple capitulating to the x86 monoculture*. On the other hand, if Apple had Solaris offered to them, they may not have bothered buying NeXT, and OSX may be based on a less exotic strain of UNIX.
* not that that's entirely a bad thing; perhaps, once Intel Macs are commonplace, smart hackers will figure out ways of shoehorning Windows code (such as, say, the numerous free VST plugins that never make it to OSX) into running on one. But I digress.