One problem with the 60's set is that it does NOT include the movies music (some of which is great, much of which is decidedly not great) which is available in a separate set. So, with the 60's set, for instance, you will not get Viva Las Vegas.
BTW, if you spring for the 50's set you may not want to get the Sun Sessions--there's one version of every tune included in the 50's set. The complete Sun sessions includes outtakes and alternate takes.