I've read the opinion that uranium has been generally favored over thorium because of the desire to portray nuclear bomb tech as something positive for the world. Harnessing the atom and all that. That would still have to be somewhat true with thorium but apparently it doesn't offer the same propo score.
A buddy on another site is a booster for life of the integral fast reactor (IFR) for which there is apparently no other available suitable coolant/energy transfer medium than liquid sodium. I'll admit it's an attractive solution in many ways - it could consume much of waste nuclear materials currently in haphazard storage and is allegedly meltdown-proof. The downside from what I can gather is that so far practically all of them have suffered debilitating sodium fires. What could go wrong? Liquid sodium separated from water by a thin metal membrane? Oh boy. Maybe if the sodium could heat another medium which is then transferred to the water/steam component - sort of a buffer step - might be more reliable.
Integral Fast Reactor - Wikipedia, the free encyclopedia