Check out what shows are on at South Bank, some good eateries around West End which is round the corner, Tamborine and the creeks are worth while but you'll need a QLD fossicking license to be on the safe side if you start checking the creeks, most likely be ok for a day trip though. Eumundi markets aren't bad for a day on the weekend, not sure what day they operate though.
GC... take it or leave it, nice beaches though, Burleigh and Currumbin have good local eateries.
The route from the Gold Coast through the Numinbah valley to Murwillumbah is lovely for a drive with the volcanic plugs and Mt Warning, stuff in the creeks and banks around Numinbah, the Rainforest Cafe at the bottom of Mt Warning has awesome food and snacks, The Persian Cake is to die for and the coffee really good! The bush walks around the base of Mt Warning are lovely, but to hike the Mt you need an early start.
Then there is N Straddie, ferry trip and great bush walks, Whale watching from the headland at this time of year, they come in pretty close. No need for 4x4.
Hopefully that helps