DaisyB writes:
... I am going to be in Spain for 8 full days, starting in Madrid.
Are you sure?? If you fly EWR-MAD you can't really consider your arrival day as a full day. You will likely be 'wiped out' from jet lag and from your TransAtlantic flight. One rule I follow when traveling: Get where you're going that first day!
I'm going with 3 other people. One absolutely wants to go to Granada, and one wants to go to Barcelona. Is this even possible?
Of course it's possible! For example, you could continue to Barcelona on your arrival day, then work your way back to Madrid and/or Granada
Is it better to concentrate the trip in the southern area to make the most of our time?
How does concentrating your trip in one geographic area make the most of your time??
What cities should we go to? Is three days good for Madrid? Thanks for all of your help!
Barcelona (2-days), Madrid (4-days incl. Toledo & Segovia) and Sevilla (2-days, would be a starting plan). You could substitute Granada for Sevilla; and you could skip either Toledo or Segovia when you visit Madrid, but I wouldn't.
From what you say you are 4-people with separate and different Agendas. If you're going to travel together, you should settle on a firm itinerary before you depart.