Its not a quick trip but I had my favourite route on a sunny weekend: out of Rotorua - east along the lakes to Whakatane, then west low level around the coast to Great Barrier Island - have Lunch there and then down south to the east of Hamilton and into the hills near Taumaruni then a nice map reading excercise to get back to Rotorua going west along Lake Taupo.
Takes the better side of 5 hours - and I would not recommend taking the wife along - I did it only the once
- but its a great flight on a warm, sunny summer afternoon.
Otherwise a quick trip across to Masterton and a car to the tui factory was another fav - of course, you dare not come back the same day if you do it properly...