Tongariro Northern Cicuit - alternate routes

Planning on doing the RTM and NC combined in February. I have done the traditional NC before, including the peaks etc. but this time I'd like to explore some alternate routes in the area. Last time I was there I did do a slight variation of the NC by going up and over Tongariro, rather then the standard South Crater track. I'm thinking: - To Oturere Hut via upper Tama Lake - From Mangatepopo to Oturere (or Waihohonu) via the southern side of Ngauruhoe (between Pukekaikiore and Ngauruhoe) - traversing North Crater - any other suggestions Does anyone have any info, maybe even GPS track data.