We didn't hire a camper van so can't help on that side, but did do an organised self-drive from Sydney to Cairns. All the hotels along the route were prebooked which suited us. The trip took 11 days and if we had had (much) more time I suspect it would have taken us several weeks to see everything. You need to plan exactly what you want to see, check mileage (distances can be huge as you forget how big Australia is) so that you aren't spending too long in the van - you are on holiday after all. Brochures are a great help as to what sights you would see along the way, most TOs offer self-drive trips (like ours) so pinch their ideas! Go into the local tourist information offices once you start your drive, they've got suggestions of places to visit that perhaps don't feature in the brochures. This was how we discovered Paronella Park (beautiful gardens and forest guided by locals). This Park is between Townsville (we didn't rate this place) and Cairns, but since they built the new highway most people drive by not realising its there. Incidentally, what is called a highway in the most part is no more than a single/dual carriageway!

I guarantee you will have a great time. We go back to Oz in February and will be doing a lot of driving in Western Australia so are really looking forward to going again. Once you've been, you just want to go back again and again.

It's about 1500miles from Sydney to Cairns. A long drive and as the previous poster said most of it on single carriageway roads.
I think the main camper rental companies are Britz, Maui, Kea and Apollo, a cheaper option are Backpackers who use older vehicles(though I am not sure if they have the whole range of sizes) I expect there are other companies. I used a Kea Camper in New Zealand and found their vehicles and service very good. Be aware you will probably have a large one way drop off fee for the camper in Cairns. I would think you should be booking as soon as possible.
The main places for interaction with wild dolphins are Monkey Mia in West Australia which is thousands of miles from where you are going and I believe there is something similar in Port Philip in Victoria, again a long way south of your planned journey. I have read that you can often see dolphins in Byron Bay (on your route north to Cairns) and in Queensland at Hervey Bay, more famous for spotting Humpback Whales but sometimes dolphins can be seen in the area, but both of these places don't have interaction with them.
I think you should book your flight from Cairns to Sydney soon as lots of other people have the same idea as you for New Years Eve and the flights will be getting booked up.
I can't give you any advice about the Sydney Harbour Cruise, I just used the ferries when I was in Sydney but maybe booking a meal in a nice restaurant/pub with a good view of the fireworks would be a cheaper alternative, and save the harbour cruise for daytime. I'm sure where ever you are in this great city on New Year's Eve will be a memorable experience.

Hi rosieg03

We are in Sydney for New year ,we booked our harbour cruise with http://www.captaincook.com.au/home.asp way back in February at the time we were told it was on a first come first served basis as demand is so high, we had seven days in which to pay FULL amount and yes its expensive!! but i hope it'll be worh it
i would make enquiries ASAP to avoid disapiontment
give http://www.freedomaustralia.co.uk/index.asp they may be able to help

Edd

Some great advice thanks everyone so far this is where we have decided....

Thinking logically about the camper van, whilst in theory sounds great fun but actually you are right, we need to make the most of our time in this fabulous country. So we are flying from Sydney to Brisbane spending five days there then going up to Cairns (possibly by train)?? In between which we were thinking of spending Xmas eve/day at Whitsundays, then flying from Cairns to Sydney on the 30th (now booked on your advice) and are booked at the Swissotel until the 4th January. Im sure that there will be lots for us to do and whilst it is possibly more expensive staying in hotels, it will probably be more comfortable and convenient. Thinking about hiring a car whilst at Brisbane/Cairns to be a little more independent rather than catching coaches everywhere.

New Years Eve, have looked at the cruises, think that it has to be done, who knows Ed, we might even be on the same cruise!
Also going to pre-book the bridge climb - the whole thing is really exciting, if not a little stressful!
Thanks so much for your help, Im sure that I will be back here again before the 13th December for more advice.....

I hope you will be here a lot before December Sounds like a great holiday

rosie
Brisbane is an easy city to get around and depending on where you are wanting to go the local train service is excellent, when I was there I used it to get out to the coast, it was fast and clean and a cheap alternative to hiring a car. Of course with four of you sharing expenses it's not so expensive to get a car.

Judith

Thanks for all the advice so far - the trip is coming together nicely, but have a bit of a dilemna which is:

We are staying in Brisbane until the 20th and we are then planning on going to Fraser Island for two nights, checking out on the 22nd we then wanted to go to the Whitsundays for a further two nights before going on to Port Douglas. Problem is that the islands are asking for a four night minimum stay and Airlie Beach is booked up. SO.......we are considering after Fraser, driving up to somewhere like Mackay, staying overnight there and then moving up to Whitsundays to do a day trip, then staying somewhere like Townsville before driving up to Port Douglas...anybody know how long it might take us to drive from Fraser to Mackay and so on or indeed any further tips/ideas greatly appreciated.

Many thanks.

For dolphins, a night in Tin Can Bay, not far from Fraser, where you will find a reasonable Motel, free transport from there to the Country Club for an excellent meal, and feed the dolphins at around 0800 every morning.

I there sounds like you are doing the same as us! There are 3 of us, we head to Sydney on the 6th December, doing the bridge climb on the 9th then picking up hire car on the 10th. The plan is to drive up the east coast stopping off on the way. We have a flight booked on the 30th from Cairns to Sydney to get back in time for new years eve and we have booked a party boat for new year eve can't wait!