Denizli is the commercial and transportation hub of Aegean Turkey. It is nesteled against the hillside at the southern side of the Buyuk menderes river plane. It's a busy place partly because of nearby Pamukkale and its travertine pools but mainly because it's the main commercial hub for the agricultural produce coming from the region. It's also the place where you probably need to go if you're in need of cash.
Don't let it's looks deceive you when you arrive at the Otogar once you proceed beyond the main thorougfare and it's dreary concrete facades which are repeated throughout the city, you find there's a lively market and all sorts of eateries. Since tourists don't really come here, you probably won't be harassed.
You can take a dolmus from here to Pamukkale they run approximately twice an hour.