A recent book from the Indiana University Press is for those who are interested in or wish to play Milán: "Luis Milán on Sixteenth-Century Performance," by Luis Gásser, 1996. The author is at the University of Barcelona. It is recommended highly by a guitar-playing friend of mine.
Christopher Wilson gives a good survey of vihuela music (from Milán through the Spanish Renaissance) on "Vihuela Music," Virgin 0777 7595962 8
Other cds I recommend are "Al Alva Venid, Musica Profana de los Siglos XV y XVI," Glossa, GCD 920203. Also "La Folia, 1490-1701. Jordi Savall, Alia Vox AV9805.
For Bonnie S., one that is highly recommended, and that I have ordered, is the Codex Huelgas, esp. the second cd, Polifonia Inedita, Voce Huelgas, Virumbrales, on Sony Hispanica SK 60844. Rates 5 stars in Goldberg.

Some time ago, someone was looking for Sephardic music from Spain. I haven't heard it, but one cd is "Canciones sefardies," Saraband, on Sonifolk 21115. A review I have pronounces it "not too bad."