For a 2-week - only Spain roadtrip - I might suggest the following:
- Fly into Madrid
- Hit Madrid, Segovia, Avila
- Drive south hitting Toledo on the way
- Visit Cordoba, Seville, Arcos de la Frontera, Rock of Gibraltar, Malaga, Ronda (Southern Spain will be hot, but the cities in southern Spain are amazing to see)
- Head north. Granada
- Valencia
- Barcelona, Montserrat
- Back to Madrid (while in Madrid visit the Royal Palace, Prado, etc.)