Hi, I'm from Singapore and will be in USA (Las Vegas, LA and SF) for 2 weeks. I'm looking for a prepaid plan with unlimited data preferably. I'm not so concerned about talk time and text because I'm primarily going to use whatsapp and viber/skype for that purpose.

I have a iPhone 5 unlocked. I've looked at T-mobile and AT&T prepaid plans and am wondering if the T-mobile Prepaid - Pay by the Day plan and the AT&T GoPhone $50/month plan are the correct ones I'm looking at?