Talk:Spain/@comment-66.58.192.103-20160212194254/@comment-26674008-20160213080607

Since you have an iPhone 4S, you can forget about the 4G/LTE coverage as you'll get 3G only. You'll want a network that supports "tethering" and also provides iPhone "profile" which you can see by the article isn't the case for all networks; some block tethering entirely and some allow it but don't give the iPhone profile for it, so you can't use the hotspot. Unfortunately this article doesn't say for some networks.

Orange is the only network you can buy SIM cards to be shipped to the US (on eBay), that I know of. The rest you have to get in stores, because of showing passport requirements. You want to make sure you get prepago and not contrato sin commitment  which are contracts, which are relatively easy to get as a foreigner, but you have to cancel when you leave.

I don't know about coverage in the southern 2/3, but data is pretty cheap in Spain, you could probably get a second SIM if the coverage turns out to be poor.