A Suggested 14 day (once there) Australian Itinerary.
 

I'm starting to consider a trip to Australia next summer. I can only go during our summer due to my job. I'm a single woman in her 40s who travels alone a lot. I know I want to see Sydney and a town/city on the barrier reef coast area. If I added one more area/place what would you suggest? I realize I'm likely looking at a flight or 2 within the country. While $ matters I will work that out once I have an idea of an itinerary. Thank you!

What do you like to do? Cities, beaches, mountains, countryside? Art and museums, food and wine, hiking, ???

Sydney + GBR + one other place would be about right for 14 days - I wouldn't try to do more. The obvious candidates are either Melbourne or Uluru. I'd vote for Melbourne but then I'm biased ...

Melbourne is a world-class city with lots to see and do, not only in Melbourne but also in the surrounding area. It's generally recognized (except by everyone in Sydney) as the sporting, shopping, cultural, food and wine capital of Australia.

The Yarra Valley wineries are an easy day trip from Melbourne. If time and interest permits, visit the Healesville Sanctuary.
http://www.visityarravalley.com.au
http://www.zoo.org.au/HealesvilleSanctuary

Take a day or two and visit Daylesford and surrounding areas. Perhaps go via Ballarat and visit Sovereign Hill and then on to Daylesford for the night and then back to Melbourne. You could do it in a day but much nicer if you have the time to stay. In Daylesford, have lunch or dinner at the Farmers Arms or the Mercato. Visit the Convent Gallery.
http://www.visitvictoria.com/Regions...on-Ranges.aspx
http://visitballarat.com.au
http://www.sovereignhill.com.au
http://conventgallery.com.au

Take a day or two and drive part of the Great Ocean Road.
http://www.visitgreatoceanroad.org.au

Explore the Melbourne CBD (central business district). Spend a lifetime exploring Melbourne's lanes and alleyways. Find the myriad of hidden bars and restaurants and shops - up a flight of stairs, down an alleyway, hidden behind an unmarked door. Stop for a coffee (anywhere but Starbucks). Take a tram to St. Kilda. Go for a walk in the Botanic Gardens and visit the Shrine of Remembrance. Visit the Old Melbourne Gaol, where Ned Kelly expired. Explore some more of Melbourne. Eat in any number of world-class restaurants. Go to a footy game at the MCG.
http://www.thatsmelbourne.com.au/Pla...lacestogo.aspx
http://www.visitmelbourne.com/Region...ine/Cafes.aspx
http://www.thatsmelbourne.com.au/Pla...ndArcades.aspx
http://www.visitmelbourne.com/Videos...ne-videos.aspx
http://www.visitvictoria.com/Regions...or-sports.aspx

For the Great Barrier Reef, the usual entry point is Cairns and you can fly there from Sydney or Melbourne. However, I wouldn't stay there - stay in Palm Cove or Port Douglas, about 25 minutes to an hour up the coast. You can do reef trips from any of those locations. Most visitors probably also go to Kuranda.
http://www.palmcoveaustralia.com/
http://www.kuranda.org/

If you can be more specific about what you do and don't like, I'm sure others will have plenty of suggestions.

As you will probably be going to Cairns, why not explore its hinterland. Lots of beautiful scenery and some rather dull expanses once you get into the 'outback' areas. This is the place to see the wildlife in the wild too. If interested in geology and natural history there is enough to keep you busy for years.

Once we know a little more about your interests we can add more detail.

You know I've been on these boards so long I should know better than to leave out interests. I am interested in wine, (so visiting a wine region sounds ideal), cultural things and in terms of Australia more interested in the coast than the interiors. I enjoy large cities, but also like to have a quiet couple of days in the middle of a big trip such as this. While I enjoy wildlife, you'll never find me reading any type of outdoor magazine. Traveling alone, I'd like to be in areas that are safe and where being a single traveling woman will be easy in terms of dining and things to do.

Melbourne it is then!

From Melbourne, there are wineries on the Mornington Peninsula but the Yarra Valley is the more recognized area. It's an easy hour or so drive from Melbourne. Start at the Yarra Valley Dairy Company for a cup of coffee and a cheese platter. Visit Domaine Chandon and do the self-guided tour (bearing in mind there is never very much to actually see (in terms of activity) in a winery), then try the tasting flight of their sparkling wines. Visit the art museum at TarraWarra and have lunch there, or at Yering Station or at De Bortoli or maybe Tokar Estate.
http://www.yvd.com.au
http://www.domainechandon.com.au
http://www.tarrawarra.com.au
http://www.yering.com/index.php
http://www.debortoli.com.au
http://www.tokarestate.com.au

If you want "a quiet couple of days", go to Daylesford. It (and its neighbour Hepburn Springs) are the spa capital of Victoria. As suggested, perhaps go via Ballarat, stay the night in Daylesford and relax ...

If you like the coast, then take a couple of days to drive part of the Great Ocean Road ...