1976 is a very sad year for me. We have so much concerts from 1975 where Elvis is in a very good mood, enjoying what he was doing, gave away great shows and also looked good.
But then in december 1975 Elvis returned to Vegas and seemed to have gained lots and lots of weight.
In 1976 it was obvious Elvis wasn't going to loose it (and also gained even more). There are many shows in 1976 that are dull, inspired and showed a very out of shape Elvis. At the end of 1976 he seemed to re-take some control over his weight (and hapiness), and he even did some very good shows.
1974 is (to me) a great year, with many great, full speed ahead shows, great setlists, a healthy (and slim!) Elvis, lots of karate and also good energy. There are a handfull shows where Elvis was a bit out of control, but even with those shows (like college park) he seemed to enjoy himself and doing the best to give away a great show.