I remember only taking the first 5 steps (just for the picture....). In Palenque we went all the way to the top. Going up was easier than going down again.
You can't climb this pyramid anymore at chichen itza, think some people died falling down it as the steps have worn away so much. Means better pics though! Needed to go to Coba to climb one, that was a real steep one too, quite scary :-)