The most comfortable cars that I ever ridden in were the fully loaded American made land yachts of the late 60's - early 70's
Power steering, power seats, power windows, power antenna, power...everything! tinted glass, am/fm stereo, 8 track or cassette and what I remember most was in the Summer the air conditioners being more like whisper quiet refrigeration units, I mean deliciously COLD!
So for me, I would say any of the Cadillacs from that era along with a case of Bill Basie's recordings from his late 50's to mid 60's songbooks.