Omahau Downs, the farm holiday accommodation owned by Sean & Nicola Jones, has been my favourite place to stay in Twizel on a number of occasions now. There are several forms of accommodation from which to choose. In late May 2014, I stayed in the 2 bedroom cabin with its verandah on two sides. It has all the facilities of a small home and is most comfortable. One bedroom has a queen-size bed and the other, 2 singles. The kitchen is all one would want for self catering and is part of an open-plan room along with the dining table and lounge. Free WiFi is available. As you might imagine in late May the temperature was getting cool but the cabin with excellent heaters, was as cosy as one would wish.
If you're visiting the Twizel area; Aoraki (Mt. Cook), Lake Pukaki, Tekapo, the Mt. John Observatory, Omahau Downs with its panoramic views would be the place to stay. Omahau's website is http://www.omahau.co.nz