Using (esp. liquid) fabric softener on towels does make them LESS absorbant because it coats the fibers to keep them fluffy. They might feel better, but it will take you forever to get dry
The vinegar leaves no smell as long as you put it in before the rinse cycle (or just put it in the fabric softener compartment) - you don't need a lot, less than a 1/4 cup, same as most fabric softeners and it rinses out completely.