I only did the day tour (fabulous, be sure not to miss your time slot or they won't let you in). Not sure it's worth going there at night (others can weigh in on this point) but to clarify the Generalife is the gardens, Palacios Nazaries is the main palace building. I caught the sunset view of the Alhambra from the Albayzin neighborhood, catch one of the mini buses and get off at the San Nicolas Viewpoint - SPECTACULAR. You'll be there with a lot of others, but it's the most perfect view of the palace lit up.
Regardless, take your RS book because there are few handy maps or guides in the Alhambra. Take snacks and water too, not many of those to choose from either.
Have fun - it was one of the best highlights of my three week trip, lived up to every expectation and then some. If you're really into it, check out Washington Irving's "Tales of the Alhambra" before you go, you'll see the rooms where he wrote it and his stories will come alive before your very eyes.