Cs-137 will be produced anyway in nuclear fission reactions. So, why not design some fully automized factory in which you separate it and make some compound that contains it? This material would then presumably be red hot from all the heat generated by radioactive decay.
You can then make a heat exchanger out of it and use it in a powerplant or to produce warm water for homes. After 30 years the power of the Cs-137 heating element will be halved. You then recycle it in the nuclear waste reprocessing factory. The ability to do this safely depends on what we can do with machines and robots.
Robot technology is predicted to become much more powerful in the near future, so perhaps we should store radiaoactive waste in easy to access places.