Unlocked GSM Phone Suggestions?

The goodybags are only valid in the UK.
If you are setting up before you fly,US credit cards work on the online giffgaff register site.

You buy credit , but then have option to convert to the goodybag packages.The goodybags are much better value.
If you leave some credit after buying the goodybag it will handle the international calls.
For peace of mind leave SIM out of phone till you get near UK, accidently roaming from the US would eat your credit in a couple of minutes.
International calls while in the UK are pennies per min.The rate to US has dropped to 3 cents.
What would be VERY expensive is calling the US if you take that UK registered SIM to France.

Calls and txt in France ( or other EU country, to an EU) will be more expensive,but still about half of the travelphone rates.
I have sent you a Pm too

In general, allowing for the fact I have never heard of 'Giffgaff', all SIM cards in Europe work in other European countries. This is called "International Roaming". Yes, the cost will be higher using a phone from country 'A' in country 'B', but not exhorbitant.
The EU consumer protection authorities have been cracking down on excessive roaming charges, but this only applies to roaming between EU countries. Raoming charges outside the EU can still be excessive.

You do not necessarily need to get a new phone, if your current phone is unlocked and compatable with the European Standards, you can just get a new SIM card; or even use yor existing SIM card, check with your current provider.

If you get a smart phone you can get a free data moniter
Data roaming in France will not be crippling but is more expensive.Theres a mandated cap think its approx 27c a MB
In the settings , disable auto updates or choose option to only allow via wifi, otherwise the phone may download lots of mb in the background. Better still ,turn Data connection off unless you need it and wifi isn't avaliable
For text web browsing the mb is trivial but youtube or streaming radio will eat data like crazy.

Thanks so much for your help guys! Unfortunately my phone is CDMA only, so it won't work in the UK.

tia,

You could buy an unlocked quad-band GSM phone off E-Bay or similar sites, and then just use it with a SIM either purchased in the UK or from one of the travel phone firms such as Roam Simple, Cellular Abroad, Mobal, Telestial or EuroBuzz. Many of these use phone numbers based in the UK and also consistent rates for using in other parts of Europe. Check their respective websites for details. I'm very familiar with cellular networks and have also never heard of "GiffGaff".

If you decide to buy a local SIM, stop at at Carphone Warehouse when you arrive in the UK, they'll be able to set a plan up for you.

Giffgaff is a Mobile Virtual Network Operator which is completely owned by O2 and operates on its network, but is run as a separate business. Its customer service is entirely online which may or may not suit.