I visited Pamukkale a couple of years ago and must admit to being a little underwhelmed. Most people though thoroughly enjoy the experience. We went with a tour group and stayed overnight in a nice hotel where we could bathe in the thermal pool.
We were staying in Side at the time and the journey seemed endless, Didn't help that it was snowing at the time so was very cold and grey. I think it would be a long day if you don't stay overnight. Despite the bad weather it was very crowded. Like anywhere else it's best visited in good weather.
I did find the history of the place interesting but am still not sure it was worth the long journey to get there. I'm sure many of our members will have a much more positive experience than mine.

I had a feeling that would be the case, 5 hour coach jounrey to me = 10 hours theres and back which is practically a full day of travelling, i didn't go see the pyramids in Cairo when i stayed in Sharm due to the travel time cos im not a big fan of long coach trips Think i may just spend another day by the pool or the beach instead!