Te Puia in Rotorua is too expensive, if you have transport go to Waiotapu instead

If you are travelling to Rotorua for the first time most people will say go to Te Puia (which used to be called Whakarewarewa). This has become a real tourist trap over the years and is very expensive (currently minimum $40 pp). Instead go to Waiotapu which is currently $27.50pp and is 20 minutes drive south of Rotorua. Personally a better experience of boiling mud, sulphur and hot pools stuff.

Waiotapu - http://www.geyserland.co.nz/
Te Puia - http://www.nzmaori.co.nz/

And if you have time drop after Waiotapu drop by Waikite Valley Thermal Pools which are better than the Polynesian Pools in Rotorua and cheaper again. It will be another 10-15 minutes driving but so worth it. Sat Nav will help if you don't have a good map.

Waikite Valley Thermal Pools - http://www.hotpools.co.nz/

If you don't have transport you can still get tours that will do both of these. See tourist information or your hotel reception for details.