I always take my iPad with me when I travel, but traveling abroad is a mixed blessing because thanks to AT&T's exorbitant charges for data service I'm usually limited to hunting for free WiFi hotspots. Last time I arrived in Mexico, AT&T informed me via text that it'd cost me $20/meg for data, which is insane. There are, of course, the "super affordable" (according to AT&T) international data plans/packages you can sign up for, but even that costs $100/month for 275meg, or six times as much as the $15/250meg domestic plan. And 275meg doesn't get you nearly as far as AT&T would like you to believe.
So when I traveled to Switzerland for ten days, I decided to simply get a SwissCom SIM upon arrival (a SwissCom store is right in the airport). SwissCom charged me 20 Swiss francs for the SIM, but that included a 20 franc credit, so the SIM was free. Prepaid monthly data plans are 19 francs for 300MB or 39 francs for 2GB. I took the latter. The paperwork took 15 minutes and I was on my way. SwissCom has excellent coverage in Switzerland and being able to use the iPad without having to worry about running into the limit or incurring huge AT&T charges was terrific. This way I could use my iPad as a GPS (Hertz failed to deliver the promised GPS in my rental), browse as much as I wanted and needed, and also use a couple of very helpful apps (ZVV Fahrplan and Wemlin) to navgate the terriific public transportation system in Switzerland.
Getting a SIM card for a particular country doesn't make sense for those who travel through multiple countries, but it's a very economical solution if you vacation in one place.