Wasn't there supposed to be a ring of observation lounges around the rim of the saucer?
The rim of the saucer was supposed to be one deck high with the windows above and below sunk into the ceiling/floor to create a "wall of stars" effect with the wall between the windows (which housed the sensor strip on the outside of the ship. This area was supposed to basically a long hallway with chairs, tables and other gathering spots. I guess the budget didn't allow for even a portion of this set to be done given the budget limitations and the space limitations of the studio. IIRC this is one of the reasons why the rim of the saucer (in universe, at least) has unlit windows, this corridor was supposed to be dimly lit for atmosphere.
Ten-Forward was designed as a compromise with the slightly increased budget in S2 to the "grand corridor", even though it didn't fit into the design of the ship it was fudged to.