Elvis' movies are often ridiculed, and rightly, as bubble-gum C-grade films which were churned out as nothing more than lengthy advertisements for their star, who was continually thwarted in his desire to be a real, and respected, actor. However, hidden in those often terrible pockets of celluloid was some pretty wonderful music. Not his best but there are a number of gems worth digging for.
1. Blue Hawaii
In 1961, "Blue Hawaii" was made and became one of Elvis' biggest and best-loved movies. It also ushered in the beginning of the "Elvis Movie," the first of the beach-and-bikini-style films; but for all that, it remains the best of those, the most "real," despite the amount of music that was crammed into the film.
2. Easy Come, Easy Go / Speedway
This was the ninth of a series of Elvis movie soundtracks from his 23rd and 27th films. The album includes alternate takes and songs recorded for, but not used in the films. 
3. G.I. Blues
With some of Elvis' best recordings of the early '60s, G. I. Blues is a terrific listen by itself, but the CD contains many alternative takes of all the best of the songs. With the delightful "Wooden Heart," the bluesy "Tonight's All Right For Love" and lovely, lyrical "Pocket Full Of Rainbows," it's simply a terrific listen.4. Jailhouse Rock / Love Me Tender
This collection was part of a commemorative release surrounding the 20th anniversary of Elvis' death. Along with the original songs there are several alternate takes as bonus tracks.