Pamukkale is awesome! Do NOT skip it. Fly into Denizli, which is about one hour from Pamukkale by car. You only need one day to see Pamukkale. I don’t know anything about Laodicea, so I won’t comment on that. Pamukkale is about 3 hours by car from Ephesus. Depending on what time you will arrive in Denizli, you could stay overnight there or in Pamukkale. How many days are you planning on being in Ephesus? You could easily fill 6 days with Ephesus and day trips to other also amazing ancient sites. If you need a hotel rec for Ephesus, I recommend the Stella Hotel, which is high on a hill and has spectacular views of the Aegean and the port (ask for this view). They served a nice, basic, but high quality breakfast too.
If you want to arrange for guides and drivers, let me know. I had guides and drivers so I wouldn’t have to drive or find buses. It was wonderful.