Not a big deal but my two stainless revolvers, which are not used
very much, show a dark discoloration on the trigger that solvent and elbow grease are unable to remove. I'm sure there must
be some trick that I'm not aware of to make the trigger look as handsome as the rest of the piece. Suggestions?

If the triggers are a dull silver in color, they're carbon steel with a flash coating of dull gray hard chrome.
You can't polish these parts without damaging the chrome, exposing bare steel and allowing rust.

If you just can't live with it, you can send them out to a gun re-finisher to have them stripped and re-plated with dull hard chrome.
Most of the gun re-finishers offer special pricing for small parts like hammers and triggers.

After S&W stopped hard chroming the hammers and triggers of stainless revolvers, they simply used the same color case hardened parts they used in blued guns.
These parts have a dark, mottled look typical of color cased parts.
In this case, you can have the parts hard chromed.
Again, if you polish the parts, you'll remove the thin colored coating and expose soft metal under it, which will again, rust.

Many thanks for your thorough answer to my trigger question.