Stay away from Nyquil. It is the most nauseating stuff, ever made.
If you have a dry cough, you want a suppressant. If its a wet cough, you want an expectorant. For a stuffy nose, a decongestant. According to an FDA study, cough syrups with guafenisin provide the best results. As a smoker, I get coughing fits, in the middle of the night and the guafenisin syrups let me get back to sleep.