You could try http://www.holidaysallover.com.au/tours/ not sure if it is exactly what you are looking for but they may be able to help.

Do you want to see stuff along the way, or just get to cairns? It is quite a long way to travel if you are only here for three weeks. My reccomendation would be to book a cheap plane fare. There are some nice places that you will miss up the coast, but more time to see other stuff would be valuable I think.

You can get a return flight for less than AU $200.

I don't really know of many tour companies that operate up and down the coast - I don't think it is overly popular.. What were you hoping to see, maybe I can help.

 Hi:

Just to let you,i drove up from Sydney to Cairns (ok,my hubby did most of it)...and if you only have three weeks you might want to look up other options,we left Sydney on a friday at 5.00am to avoid traffic getting out of there,being a weekday traffic is heavy everywhere...then we drove,and drove,and drove,only a quick stopover at the beach in Coffs Harbour,and kept driving,we wanted to get here asap,so if you want to stop and see places on the way then you will need at least a week.First stop overnight was at the Sunshine Coast,we left early again in the morning,next stop overnight McKay,next morning drove To Cairns,stopover at Townsville for ice cream and then got to Cairns Sunday at around 5.00pm...Overall it was a long trip,tyring,nice most of the way except around Rockhampton,nothing much to look around(at least other places looked more greenery)....we did spend quite a bit of money on petrol,some food,and motels.If you can fly up you will use that money and time getting around all the beautiful places around here.Good luck!!By the way,July is high season in Cairns so plane ticket might be a bit more than $200 bucks.

This almost sounds like flying is the way to go. I usually prefer to drive, since I can see more of the country this way, except if it costs too much time and there is not that much to see. So how was the drive?

Thanks for all the advice.  I am still to book my trip over to Australia, and still trying to figure out how best to use my limited time.  I'm not a fan of staying in one place for too long (couple or three days at most) so thought a trip up the coast may be the best way to spend three weeks.  I'm aware it's a very long way, in fact it looks like driving from the UK to North Africa in distance, but nevertheless I'm sure it would be a real taste of Australia.  However, if there's not much to see on the way up to Cairns and there are other trips worth doing then I'm open to ideas.  If a flight to Cairns from Syndey is cheap, then trips from there round the north may also be good.  Any more advice would be very welcome.

 Thanks!!

 Matt

I also prefer to drive around the Australian Coast as then you can stop and go when ever you feel like it. You can take your time to see every thing you want to see. When you arrive in Cairns make sure you visit Kuranda up on the Tablelands, you can get there in three different ways. To drive is interesting and pleasant but the alternatives are so much better. The train runs on what is arguably the finest stretch of scenic railway line in Australia. One section actually runs across the face of the Stoney Creek Falls and the views are nothing short of amazing. Trains depart Cairns daily.

Can anyone tell me how long it takes to fly from Sydney to Cairns and whether you can fly from Cairns or Brisbane to South Island, New Zealand.  How long a flight would that be?  Or is it better to return to Syney and go to New Zealand from there?  Also, we have 18 days and are looking at flying to Sydney from Los Angeles.  From Sydney we were hoping to fly to Brisbane or Cairns and visit the Great Barrier Reef and then return to Sydney and take the train to Broken Hill and Adelaide before flying over to Kangaroo Island.  Finally we were thinking of going to the South Island of New Zealand either from Adelaide or Sydney and returning to Sydney to fly home.  Is this crazy???  Can we come close to fitting all this in in just 18 days.  Wish we had more time but both my wife and I work and we cannot get away for any longer.  Thanks for any thoughts on the subject.

Yes, you're crazy.  First, the flight to Sydney is about 17 hours long.  Second, you cross the international dateline, so if you leave on Saturday, you will probably not arrive until Monday.  You get it back when you return home, in that the trip that direction will take only one day.  Sort of.  Anyway, out of your 18 days, you will spend close to four of them getting there and returning.  Then you will effectively lose a day to jet lag each way.  So six days are gone, and you have 12 left.  You want to take five flights and a train trip during that time.  That leaves you with 7 free days to do something other than travel.  Of course, part of six of those days will be taken up with preparing to leave the next day.

 My suggestion is to look into an open jaw ticket into Sydney and out of Cairns.  Spend some time in and around Sydney, then head up to Cairns, go out to the reef, and visit the Daintree Rainforest or maybe fly to Cairns via Ayres Rock or Alice Springs.