yeah if you want realism then sprites are the way (as you map real images to them) so you cant get better than a real image!

I really think that using a combination of particles and fluids gives very good explosions smoke etc (T3 I think used fluids for the nuclear explosions at the end)

You could use particles with fields on each so they dont go over the top of each other (the playback speed isnt too bad i've found) even with lots of fields) if you want it to pour. (maybe with the blobby particle surface...)

Just another thought