I went to Spain on a family trip this summer. We spent 3 weeks in Madrid, up north in Leon, and then down south in Cordoba, Granada, Ronda, and Seville.
For what it's worth… I took my 5D2, a 16-35 f4 IS and a 24-105 f4 IS. Out of the 2200 photos I took while there, 1550 were on the 16-35 and 650 were on the 24-105. I usually only carried one lens each day and decided which one to take based on what we were planning to do. Anything indoors and I would take the 16-35. Mostly outdoors I would stick with the 24-105.
I would definitely prefer a 16-35 for the Alhambra. Having that ultra-wide just opens up so many possibilities for indoor photos. Make sure you get your tickets ahead of time, otherwise you'll be stuck paying tour prices the day of.
Also, if you haven't solidified your itinerary yet, I would highly recommend checking out Ronda. The bridges and architecture are pretty amazing, and it's a great place to do a little bit of hiking to get the typical Tuscany-style countryside views. It was one of our favorite stops on that trip.
Hard to say what I'd recommend for your situation. If you bring a 16-35 or a 24-__, you really wouldn't need your 35 prime because you would already have that focal length covered. A 16-35 is really ideal for Europe, but I'd also want to have something with a little more reach. Maybe an 85mm or 100mm prime if you didn't want to carry two heavier zooms.
As far as picking a 16-35, I went with the 16-35 f4L IS and have found it to be great for travel. The IS is really effective, it's much sharper than the 16-35mm f2.8 II, and relatively light weight. The 16-35mm f2.8 III is supposedly a small bit sharper, but doesn't have IS (I shoot mostly handheld) and is a lot heavier and more expensive. Even if price was no object, I'd still pick the f4 personally.