I’d like a visualization that simply displays the actual query executed against the database, with any input fields replaced with the user input parameters.

When sharing query results with certain people who don’t have access to Redash (ex sharing dashboard externally) I like to share the query too. It helps people interpret the results. Even if they are not familiar with SQL they are often more familiar with the data and can verify whether the analysis makes sense. They also end up gradually learning SQL which is a plus. Typically I want to show people 3 visualizations for a query: table of data, chart of data, and the SQL query that generated the data.