I'd pick one country for two weeks. Otherwise, you will spend a lot of your vacation in airports.

The free online guides here might be a good place to start planning. Also try you local library for travel guides, Lonely Planet is the most detailed for Australia.

Not only would I pick one country for your two weeks, I'd pare it down to only one island if you choose New Zealand and 2-3 states if you visit AUS, less if you've got Western Australia in the mix.

Don't underestimate the size of Australia, and the travel distances between attractions in NZ, which looks small on a map, but the roads are narrow, they're usually one lane in each direction and they're quite squiggly.

You'll find countless fabulous walking tracks in NZ (and no snakes to worry about), bush tracks, diving, wonderful beaches, and funky country towns in Australia, in addition to all the tourist sites you've undoubtedly heard about.

Another major point to consider in addition to where, is when, as in time of year. I suggest you try to avoid school holidays, Christmas, January and Easter in both countries. These are very busy travel times, rates are high and places are busy. You can find exact school holidays online for both. You'll also want to look at weather, as a good time to visit NZ isn't necessarily a good time to visit AUS, depending on where you go.

You've got alot of reseearch ahead just to decide where to go. I agree Lonely Planet is a good place to start for both countries.

We are about to go to Australia for the first time in April. (The trip timing is based on a wedding outside of Melbourne.) I'll just share with you what we have decided to do, in case it is helpful. After the wedding whatnot for the first few days, near the Great Ocean Road, southwest of Melbourne, we are doing 2 days in Melbourne proper, flying up to Cairns for 5 days, then back down to Sydney for 4 days. Cairns sound like a great potential base for you, as there is the Great Barrier Reef (snorkeling, scuba) plus all the hiking opportunities (Atherton Tablelands, Kuranda, rainforest, etc.)

I have to agree with previous posters that trying to do both countries sounds like a lot to take on in only two weeks...

I know the temptation is there to visit both Australia and New Zealand because they are in the same region, but based on my experience, you will do yourself a disservice if you try to cram both countries into a 2-week visit. (I have made 3 separate 2-week trips to New Zealand; I have made 3 separate 2- 3 week visits to Australia; I lived in Australia for several years).

I agree with Susan that reading guidebooks (especially the Lonely Planet series) is a good way to decide what you most want to see/do. If you choose to go to Australia, plan on 3 (or at the very most, 4) destinations. The iconic City, Rock, Reef (Sydney, Uluru, Cairns/Port Douglas) option is a good 2-week combo.

If you decide to visit New Zealand, I agree with Melnq8 that you should focus on one island. Our first two trips to NZ included both islands, but on our last trip, we toured only the South Island and that was the best trip of all. We swam with dolphins in Kaikoura; we hiked on the glaciers; we did the adventure stuff in Queenstown and we did a 3-day hike on the Hollyford Track.