I think it is worth hiring a guide at Real Palace. El Palacio Real has so much history, and if you are a history nerd or you just like history a lot, I think you’d really like the guided tour. The problem with the official guided tour is that they do not guarantee the availability of guided tours, so the only way you can book the official guided tour is at the ticket office on the day of your visit. You’d have to pay an extra 4 euros in case there is a guide available. Many tourists prefer to pre-book a private guided tour and this can be done on the Internet easily.
Personally, prefer an audioguide as you can stay at the palace as long as you like it and the information on the audio guide is good and adequate.
Madrid Palace Guided Tour
Royal Palace guided tour bookings can be done only at the palace; waiting times are not long even for tours in English. Expect a maximum wait of 15-20 minutes ( wait times depend on traffic). As you wait for the tour to begin, see the garden or Armory. The 90 minute official tour costs €4 per person.
If the wait times for official guide is long, pick up an audio-guide. The audio guide is well organised with additional videos and some rare paintings.
There are no night tours of the Palace. I suggest that you should come at 6pm for your visit. That way you can see the Royal Palace lit up as you leave after you are done with the visit.