2 day tramp in south island

I have a friend coming from the UK - who does a lot of hill walking mountaineering and want to introduce him to NZ tramping. Looking for a medium-hard (willing to do 8-12 hour days - but not kill myself) trip nearby wanaka/queenstown or christchurch that encompasses an over night stay in a hut - and preferable some alpine and bush terrain (a hot pool wouldnt go amiss either).Just looking for an overnight trip as he is only here for 9 days and is spending christmas in chch with family. have though about doing routeburn or green stone in 2 day and going to milford sound then back to queenstown - but despite the fact they are nice (i actually really like the routeburn and was a nice rest from the previous tramping I had done) but it is a bit touristy. WOuld prefer a cosier smaller hut - and keen to stay in hut as is one of the things I love about nz tramping anyway would appreciate any ideas you have thanks