I did a small road trip around the whole of the coromandel Penninsula which I thought was the best part of my australia and NZ trip. that is real close to auckland. Piha beach, and raglan are meant to be beautiful. waitomo is s'posed to be good. Rotorua is only 4 hours away...you could do a weekend there. taupo is only 6 hours away, there's heaps to do there.
As for night life in auckland, I prefer the irish pubs. The dog's Bollix is great for live music and for just getting a pint. then Father ted's and the fiddler are great because they never seem to close. There are also some good places on Ponsonby road, sponge wasn't too bad...it's weird most people don't get out that way but I thought it was the most interesting section of town.
oh and steer clear of k-road!
and most importantly, if nightlife is your thing...make sure on your long weekends, and vacations, hop on the first night bus to Wellington. I can go on for days about Wellington. The basement, the "stab", mini-bar, lotus, vespa, Maya, the big kumara, mighty mighty, molly malones...and that's just a few!