Next week, my wife and I are flying to Dubai for a few days, then heading to Madrid for several days. From there, we go to Marrakech, then back to Barcelona (not ideal routing, I know).

I know UAE, Spain and Morocco all don't require visas or special vaccinations/shots when coming FROM the US, but since I'll be going to Spain from UAE and Morocco at different times, and also going from Spain to Morocco, does this change the visa requirements? My understanding is that it's just the nationality that matters (US Passport), but I don't want any surprises.

Also, any vaccination requirements? We went to South Africa a couple years ago, which doesn't require any special shots, but since we went to Kenya first, we needed proof of yellow fever shot.

Thanks