Paul Schreiber blogs about the tech behind the websites of presidential candidates. "So, you want to run a country. Can you hire someone who can run a website? ...Here's how the (declared) candidates' sites fare." There's a table comparing 4 candidates' sites based on HTTPS, URL permutations, IPv6, SSL rating, and other related qualities. Schreiber mentions that he will "update this as more candidates declare or sites change."
From the blog comments
HillaryClinton.com was using IIS (and no https) until Sunday morning, when they switched over.
The level of spanish-unfriendliness is probably ideological, not technical. The republican base - the most extreme ones who are the only ones who vote in primaries - simply does not like teh brownies. I fully expect that each republican candidate has done focus groups and found that putting a spanish version up will piss off more of their base than it will draw in spanish-speaking voters.