WordNet (r) 3.0 (2006):

seventh heaven
    n 1: a state of extreme happiness [syn: bliss, blissfulness,
         cloud nine, seventh heaven, walking on air]

Moby Thesaurus II by Grady Ward, 1.0:

86 Moby Thesaurus words for "seventh heaven":
   acme, apex, apogee, beatification, beatitude, bewitchment,
   blessedness, bliss, blissfulness, brow, cap, celestial throne,
   cheer, cheerfulness, climax, cloud nine, crest, crown, culmen,
   culmination, delectation, delight, ecstasy, ecstatics, edge,
   elation, enchantment, exaltation, exhilaration, extreme limit,
   extremity, exuberance, felicity, gaiety, gladness, glee, happiness,
   heaven, heaven of heavens, heavens, height, high noon,
   high spirits, highest pitch, highest point, intoxication, joy,
   joyance, joyfulness, limit, maximum, meridian, mountaintop,
   ne plus ultra, no place higher, noon, overhappiness,
   overjoyfulness, paradise, peak, pinnacle, pitch, point, pole,
   rapture, ravishment, rhapsody, ridge, sky, spire, summit, sunshine,
   the empyrean, throne of God, tip, tip-top, top, transport,
   unalloyed happiness, upmost, upper extremity, uppermost, utmost,
   vertex, very top, zenith