Drive Blue Mountains to Melbourne

Three weeks is a long time for what can be a full days drive.
Are you looking at a round about route ?

what time of year? also do you like coastal towns and beaches or only inland country views. or perhaps a combination of both? also is Canberra on your list of options?

We'll be leaving here in Hazelbrook in a few days. We love rural, local, water, and especially Nature. Cities only once in awhile. Haven't heard much encouragement to visit Canberra other than the War Museum. Hume Highway seems least enjoyable. We have until 20 April to reach Melbourne. Thanks for any input.

The Princes Highway (A1) south along the coast is quite pretty, and would make for a good meander if you just want to explore some of the pretty seaside towns.
We enjoyed the hikes in Kosciuszko National Park - staying in or near the alpine village of Jindabyne. Would be a nice stop if you want to see what the rooftop of Australia looks like.
The Mornington peninsula just south of Melbourne is where the locals go on weekends.
A bit further west are the Great Ocean Road, The Grampians, and the Gold Fields around Ballarat if you're interested. Should be enough to keep you busy.

the options listed above are very good recommendations.
sounds like a real quandary, as you have plenty of time also as both the inland ( hume) and coast (princess) have a lot to offer. at this time of year the weather should be great, which ever you choose. depends on how much driving you want to do?
option 1. the inland route is very open, straight road ( almost boring) if you don't go off the main rd and explore. like visiting the snow fields or canberra etc. but you could include some nice towns /areas once into Victoria, eg area around Bright and then explore parts of victoria around Melbourne , As suggested.
option 2. go over to the coast, via the southern highlands, mittagong etc (eg: don't go back into sydney) and down through kangaroo valley, heading toward nowra etc. nice scenery etc. the coast rd has some nice sleepy towns dotted along the way. jervis bay etc and you could either continue all the way along the coast to melbourne (road has more bends) and visit places in the melbourne area

as a rough guide, NSW has a lot to see but is spread apart, whereas Victoria has very similar things to see but are much closer , so maybe its worth investigating what you would like to see in Victoria and then choose which route through NSW?

Thank you for your suggestions--very, very helpful. We have about 25 towns recommended so far, so now we have to track them on a map. Fun but will be more fun visiting. Glad we headed south as Cyclone Debbie is approaching our alternate route into Queensland. Thanks again.

the cyclones usually stay north, in Queensland, so you should be OK heading south, but there may be a southerly 'change' in the weather,( coming up from Victoria etc) but these usually are only a day or so of wind and rain. hope you have a great trip.

if you are at all considering going near Canberra, don't be put off thinking it is a large city.( its not that big) being a planned city it is easy to visit things like the war memorial, parliament house, with not really that much of a detour from the main hwy. it is like no other city in Australia. ( being so planned and in its layout/roads/ monuments/lake etc) and is interesting in its own way.

other than Canberra there are no 'cities' on your trip, really only country towns.

1) a loop thru the NSW central west - places like Bathurst, Mudgee, Orange, Young
2) Canberra
3) Southern Highlands - Goulburn, Berrima, Bowral
4) Thru Kangaroo Valley to the coast
5) Kiama, Batemans Bay, Bega
6) Up to the Snowy Mountains and the Alpine Way in to Victoria
7) Beechworth, Bright, Ovens & King Valley
8) Benalla, Shepparton, Echuca
9) Historic gold mining cities of Bendigo & Ballarat
10) Halls Gap & the Grampians
11) Warrnambool & Port Fairy
12) Great Ocean Road in to Melbourne