Pamukkale is in Aegean Turkey.
Closest airport is Denizli - Cardak Airport is 65kms or 1 hour away and there are flights twice daily to Istanbul.
Izmir Adnan Menderes Airport is another alternative to the area. Pamukkale is 252 km from the airport, a drive of about 4 hours (4-1/2 to 5 hours by bus)or 6-7 hours by train. (Check TCDD for train schedule)
There are trains to/from Izmir, Ankara and Istanbul.
Bus to Pamukkale/Denizli can be found from almost all the cities of Turkey. There are virtually NO bus companies that take you directly to Pamukkale despite what the ticket sellers tell you. The bus will drop you in Denizli and then you have to catch the local dolmus to Pamukkale (about 20kms away).
Take a dolmus, a type of cheap communal taxi usually seating about 10 persons (but it's possible they'll squeeze in more), from nearby Denizli. Frequent mini-buses serve the village of Pamukkale in a 20min ride.
Even when you're way on the edge of the village, you can reach everything (the village center and the travertine pools) on foot in about ten to fifteen minutes.
The 12000 seat Roman theater of Hierapolis should not be missed.
The travertine features have their origins in the shifting of a fault in the valley of the Menderes river (between here and Denizli). As the fault shifted, very hot springs with a very high mineral content (notably chalk) arose at this location. Apart from the slightly radioactive minerals, the calcium and hydrogen carbonate react to create calcium carbonate (also known as travertine) and limestone. This is what gives Pamukkale it's whiteness and created the pools.
You can walk down barefooted in the waterfalls from the village on top. The place is crowded when the tour-buses arrive. If you stay at one of the small pensions they might give you a tour of the ruins and travertines at night. It is worth seeing the remains of the ancient city of Aphrodisias. You can rent a van from Denizli to get there. Or the local hotels run tours for approx 25 lira. Also there are thermal baths at the top of the travertine pools and the ancient city of Hierapolis with a great Amphytheatre. Of moderate interest might be Denizli it's a bit dull but there's a lively market.
The Pamukkale/Denizli area is famous for its cotton and the homewares from there are becoming sought after world wide (Arnold Schwartzenegger decked out his house in curtains and furnishings specially made in Denizli - so the story goes!) and the best place to go is the town of Buldan, about 30 minutes drive from Pamukkale. Many of the other souveniers and traditional Turkish wares that you can find in other parts of Turkey are cheaper around Denizli/Pamukkale because they are produced there.
The best and freshest food is to be found in the small family run pensions, but for a great open air restaurant where you can eat 'borek' the Turkish pancakes and gaze across the valley, try Alis on the main highway just before you come into the town.
You should try turkish national drink called Ayran, which is very healthy. It is an aquired taste though. The wines produced in the Pamukkale area are becoming quite famous and winning awards for the quality and standard
There are small family-run pensions at the village south of the travertines. Most have swimming-pools filled with the warm greenish milky water from the travertines. They also offer very delicious Turkish food.