Bannockburn and Gibbston Valley have several wineries with great restaurants, and are within 45 minutes drive from Queenstown. Nature and wildlife can be covered by a day trip to Milford Sound. You could do a bus one way and flight the other if the budget permits, and there are plenty of return coach trips with lots of stops in Fiordland National Park along the way. Plenty to do in Queenstown without jumping off anything, such as Earnslaw, Skyline Gondala, etc. Spring is beautiful - snow is rare and would most likely be on the mountains. Rain in Milford Sound makes for a spectacular display of waterfalls so don't let that dampen your enthusiasm!