It's working now. The following slice of pie was causing a hick-up earlier; I needed to add another single quote to each side of the ResType and StatusCode parameters.
Non-working code:
AND (' + @OperParam + @Date_String + ' AND AL1.reservation_type IN('' + @ResType + '') AND AL1.status_code IN('' + @StatusCode + ''))'
and the Join I used looked like this...
=Join(Parameters!ResType.Value,"'',''")
Working code:
AND (' + @OperParam + @Date_String + ' AND AL1.reservation_type IN(''' + @ResType + ''') AND AL1.status_code IN(''' + @StatusCode + '''))'
and that join needed to be changed to this...
=Join(Parameters!ResType.Value,"','")
"Nicholas"