EDIT: I started writing this before Pointdexter's reply. So some may be repeated.
There are basically four streets in all of Adelaide worth visiting.
North Terrace - You have your 'high culture' if you will. Council is pouring thousands into renovating this street. You have the Art Gallery, University and State Library along here.
Rundle Mall - Shopping strip development. Nice, I guess - but not the place you usually go to by things you need. Lively, nice atmosphere.
Hindley Steet - The street of promiscuous dealings. One side has cinema, pubs cafes and clubs, other side has tatoo parlours and brothels. Every Fri Sat Sun night it's the street for the mod-mobiles.
Jetty Road - This is in Glenelg. The above three streets are withing 10 minute walk of each other. THis one is farther away. It has the same purpose as Hindley street, but with a much nicer atmosphere, and it ends on the beach. No brothels here - lots of small shops, cafes, timezone, cinema, restaurants, pubs - then hotels on the beach front. Similarly, all you see down this street on weekend nights is a parade of japanese imported vehicles straining their 0.3 turbocharged engines to push those 23in wheels.
In two nights you have seen all in Adelaide worth seeing. All else is Hahndorf and Victor Harbour just out of Adelaide. That's it.