The beauty of Aranjuez is its greenery - it's easy to forget just how dry and dusty central Spain can be is until you come upon this town, with its lavish palaces and luxuriant gardens. In summer, Aranjuez functions principally as a weekend escape from Madrid and most people come out for the day, or stop en route to or from Toledo. If you wanted to break your journey, you'd need to camp or reserve a room in advance, as there's very little accommodation available.
The eighteenth-century Palacio Real (Tues-Sun: April-Sept 10am-6.15pm; Oct-March 10am-5.15pm; , Wed free for EU citizens) and its gardens (daily: April-Sept 8am-8.30pm; Oct-March 8am-6.30pm; free) were an attempt by the Spanish Bourbon monarchs to create a Versailles in Spain; Aranjuez clearly isn't in the same league but it's a pleasant enough place to while away a few hours.
The palace is more remarkable for the ornamental fantasies inside than for any virtues of architecture. There seem to be hundreds of rooms, all exotically furnished, most amazingly so the Porcelain Room , entirely covered in decorative ware from the factory which used to stand in Madrid's Retiro park. The Smoking Room is a copy of one of the finest halls of the Alhambra in Granada, though executed with less subtlety. Most of the palace dates from the reign of the "nymphomaniac" Queen Isabel II, and many of the scandals and intrigues which led to her eventual abdication were played out here.