The major seventh chord has a special resonance about it. It's beautiful and rich. And great to play on a guitar - cmaj7 is a great way to end a song coz you can give it a good strong strum. Same with F and G.
I have to be careful not to over-use it. I like to end vocal arrangements with a maj 7 chord, but I reckon soon the others are going to start rolling their eyes "not again!". SO I try to alternate major seventh endings with sus4 endings. Both are kind of unexpected in folk contexts where straight chords are mainly heard. In jazz of course, they're staple diet!
Mbo- I noticed when I played a maj7 chord in a HearMe session you picked up on it straight away (from several continents away!). Such is the quirky, beautiful nature of this chord!