Smiting covers so few spells anyway, I'd rather they just combined these.
Light, Alignment, Fire and Divine damage would only add Symbol of Flame, Flame Strike (all of it) and Fire Storm to the list of existing spells covered by Smiting.
Untyped damage (comet fall, blade barrier, glyph of warding) probably shouldn't ever be enhanced. Which really just leaves Soundburst in terms of damaging cleric spells, and who uses Soundburst for the damage?