The non-drowsy antihistamines work okay for runny nose/sneezing with colds as well; it doesn’t have to be just Benadryl. You could at least start with a non-drowsy one, and see if that cuts it for you.
Personally I think the main benefit of something like Benadryl when you have a cold is that it puts you to sleep, not necessarily that it works better on the cold symptoms.
Source: I’m a pharmacist.
Guaifenesin is basically a placebo, but those nasal sprays work great; I prefer them over Sudafed since they work faster and don’t cause as many side effects.