The sunshine coast is quickly growing into another gold coast with high rises along the beach.
Out of the two coasts I would recommend the sunshine coast due to the more Australiana way of life still found here.
Be very weary of expensive Noosa, on the tip of the Sunshine Coast just before Fraser Island. You have a 50% chance of stepping out of your expensive Sheraton hotel onto rocks where the beach should have been. For the past few years all the sand from that most popular beach has been washed out to sea. Council is continuously pumping sand back onto the beach, but with limited success.
I hope this can be of benefit to your future travels.