I don't understand the question, as I can't see a big roaming data bundle on Wind. I can see €3 per megabyte which is more expensive for roaming than some UK SIMs, and some of them also have fairly modest bundles which work out a bit cheaper pro rata. Outside roaming bundles, if you want more than 20 or 30 or 50 MB a day you certainly need a local SIM anyway, and they'd be better value before that.

The Mega No Limit plan includes 2.6 GB/month for €20.00/month. And for roaming:
So for €23 I don't see how I could use that much data in 10 days! Even at €.51 for roaming outside of Italy I think it will be ok since I don't plan to do much talking.

I think you might be missing something here. Were you thinking that you would continue using your 2.6GB allowance when you leave Italy?
(from: Wind - Privati - Mega No Limit)

Basically, you cannot use your allowance of Mega no Limit when you are in UK and France. The 3 Euro option you are buying into is merely guaranteeing your rate of around 3 Euros per MB whilst you are roaming. That is all. You will still need to pay for that separately. As Andy points out, 3Euros/MB is hardly a rate to write home about!

At least for the UK you are much better off using a UK SIM for your data requirements. Some UK SIMs even have similar prices of roaming within Europe to the Wind rate, but without needing to cough up 3 euros for the 'privilege' of doing so.

Yes, I was thinking that based on the quote from this page: PrePaidGSM: Wind (Italy)

I was reading it as you get €8000.00/month (~2.6GB) data bundle for €30/month, and the Roaming No Limit option lets you use that bundle for roaming as well. I guess I'm reading it wrong? Would help if I could speak Italian ;)

So then it sounds like I'm back to the drawing board again. Will any one sim from Italy/France/UK get me reasonably priced data roaming in the other two countries? I looked around and don't see any reasonable data offers for the International providers either.

So should I just get 3 different sims?

IMO, if you main need is data, then the best solution is probably to get a separate sim for each country. That's the only way you can get cheap data rates. Data roaming is expensive in general. And the international sims are not any better. In most cases, they are more expensive.

I'm realizing that makes the most sense. Any suggestions for providers with a good but inexpensive data plan in France and the UK? I did some brief research but need to do some more. Wish there were more pages like this PrePaidGSM: Prepaid Data in Italy for other countries!

Yes 3 separate national SIMs will certainly make more financial sense. I am not sure about France, but in the UK you are spoilt for choice. Most UK prepaid SIMs are free, and many will give you a free bundle of data just for topping up with £10 (or in some cases less). If yours is a 3G phone you could consider "Three". https://www.three.co.uk/Pay_As_You_G...der_a_free_SIM
The other advantage with three is that they give you free Skype access which does not count towards your data allowance. o2 have a similar deal where a £10 topup entitles you to free SMS and internet (I believe 500MB). http://freesim.o2.co.uk. I think T-Mobile have something similar too.

Other SIM's have capped data, no matter how much you use per day (within reason). Perhaps a UK member will be more up to date with the prepaid data deals than me?

Have you looked at Low-cost Europe cell phones and European SIM cards they have a data system to work in all three countries. Look at the T&C I think there is a $60.00 a year charge to keep active. I have never used them so I do not know how the service is. They charge your credit card after you use the service. It is not prepaid. They are based in NY so you get the sim before you go. I myself use local sims. This is just another Idea.

Seems like Wind is the way to go? We're starting off in the UK, going through France, Italy, Austria, Croatia and then Bosnia.

We have post-paid 3 Australia accounts, and I believe the 3 Like Home system is pretty good? Or is Wind better? We also need Google Maps access, we'll die without it, and most SIMs I have looked at including Global SIMs have INSANE data prices.

Any suggestions?

HTC Desire (UK Version Unlocked) / 3 Australia Post Paid SIM

No I do not think so. If you are starting off in the UK, you may as well just pick up any SIM for data usage there, as the roaming data rates in your other countries are comparable (if not cheaper) than Wind. This will probably be your best option even in your other countries if you anticipate light data use. The cheapest would of course be to pick up a SIM in each country, but that choice is yours. As it is France has very poor prepaid data offerings, but on the other hand Austria have very good deals (especially at Hoffer/Aldi). Just search through this forum for details.

Likewise when in Italy, if you anticipate high data use, then get a Wind card for use there. As mentioned higher in this thread, I do not think its roaming deal is anything that special.

Three like home? Does this still exist? Not in the UK at least, but you may be able to get one in Australia and Austria. Bear in mind that you are usually restricted to the use of the Three network in each country, which is often rather poor.