gistfile1.cs

var sw = Stopwatch.StartNew();
var msg = new StringBuilder();
bool error = false;
try
{
    msg.AppendFormat("Doing something with xyz {0}", blah);
    
    if (!string.IsNullOrEmpty(value))
    {
        // do something here
        msg.AppendFormat(" {0} --> {1}.", something, value);
    }
    else
    {
        msg.Append(" null str.");
    }

    if (something)
    {
        msg.Append(" blah.");
        // do more stuff
    }

    return exValue;
}
catch (Exception e)
{
    // Either throw or append and set error = true.
}
finally
{
    sw.Stop();
    if (error)
    {
        Log.ErrorFormat("{0} {1} ms", msg, sw.ElapsedMilliseconds);
    }
    else
    {
        Log.DebugFormat("{0} {1} ms", msg, sw.ElapsedMilliseconds);
    }
}