We're travelling in the USA in September/October (hiring car and driving). We start in Atlanta, thence to Tn and on to the New England area for most of our time. We want a mobile (cell) phone to keep in touch with family in Australia.
Will a pre-paid tracfone give us reasonable coverage in New England? I was considering a gsm 900/1800 model.
Any other suggestions?
Thanks

GSM900/1800 will give you no coverage in North America whatsoever.
If you want it to work you'll need it to be GSM850/1900, as they're currently the only GSM bands in use over there.
For coverage, have a look in my FAQ under OnTheRoad/MobilePhones; the link to gsmworld should give you coverage maps for the providers.

To add to Lan's always excellent suggestions, a quad-band GSM Phone would be your best option. If you want to use this with PAYG SIM's from the U.S., the handset will also have to be unlocked. I'm not too familiar with network coverage of the GSM networks in New England, however the gsmworld link should provide this information.
One other point, if you purchase the phone overseas, make sure this is equipped with a "world" charger which will also operate on 120 VAC (you will probably need a Plug Adapter though).
Happy travels!!!
Different way to do what you want.
I have a Tracfone that works good enough from coast to coast, besides around my area (New England.)
When I am out of town I often call home or text from airports in Detroit, Chicago and San Francisco with no problems.
In the U.S. you can get a Tracfone from $9.95 on sale to $19.95 from lots of stores. Drug stores, K-mart, Walmart, Seven Eleven type stores carry Tracfones and the pin numbers you buy to add minutes to the cell phone.
When you want to call Australia use a cheap calling card, also available from the same sources above. For something under $20 you will have a U.S. only disposable cell phone - sort of!
Link to Tracfone: http://www.tracfone.com/index.jsp

I have a triband phone of the type normally found outside the USA (happens to be Nokia 6230i).
When visiting the US, I just get a Cingular SIM card for $25 and use that. So far I've found coverage to be acceptable, though it doesn't always work indoors.
This approach is more appealing to me than getting a new phone because I already have my contacts in my existing phone. And of course the idea of getting a phone only to toss it in the bin a few weeks later is sort of offensive.