It really depends on the location and situation. With the new generations of reactors they can also do things like seawater desalination with the waste heat alongside power production. You also have situations where the nuclear waste heat is used to heat entire communities far more efficiently than could be done with electricity. There are also many places where solar and wind just aren't practical for various reasons. In those areas nuclear may be a good option for base load power. Nuclear is also still far less environmentally destructive than hydro.

Yes, nuclear power plants are henoiusly expensive and there are definitely areas that they shouldn't be built, but they do still serve a purpose in certain areas. Most of the flack nuclear gets is just because most of our reactor fleet was built durring the cold war. New technologies can acheive far more with nuclear power far more safely and cost effectively than those old reactors.

What about the conversion of coal fired power plants to nuclear ones? I've seen that proposed quite a bit.

Two things could remove much of the expense and increase safety:

1- remove lawsuits and NIMBYism to overcome. That's where a lot of the cost and delay comes from when building these, so if millions didn't have to be spent on lawsuits just to get the goahead to begin construction it'd cut the cost massively.

2- remove profit from the equation. Without profit motive, the incentives that encourage discarding safety in favor of profit go way down.