jim,
Using a locally purchased SIM is not always the best or most cost effective method, especially if travelling to multiple countries across Europe. In some cases it can be very difficult to top-up after leaving the country of purchase. Using a different SIM in each country is even more cumbersome, as the number and terms of the service change with each SIM.
Which solution to use depends very much on individual circumstances. For example.....
- Will the phone be used mostly for local calls with no data access required?
- Will the phone be used for both local calls as well as calls back to North America?
- Will data be required in addition to voice and text capability?
- Is it necessary to be able to receive calls from home?
Which of the "global services" have you looked at? Some of the more popular firms are Roam Simple, Cellular Abroad, Telestial, Mobal, EuroBuzz and Lebara. I've been using one of these services for several years and it's worked well. Costs for calls and text have been very reasonable, although the data costs are a bit steep. Many use a U.K. based number but provide consistent rates across most countries in Europe, and many use post-paid billing (calls charged to a credit card) so no topping-up is necessary. With some the number expires if not used for a certain amount of time, while others can be used from one year to the next.
As someone else mentioned, it can be quite complicated to wade through all the different information to find the best plan.
Good luck!