Gee whiz, Jim. You're really intending to put me to work, put a dent in today's billable hours and test the old memory aren't you? There are others around here who remember the SG days so I'll share what I remember and invite others to add their recollections and correct mine as needed.
For context, our first cruise was in January, 1995. We embarked in St. Thomas and disembarked in Barbados. The cruises after ours were Amazon voyages from Barbados to Manaus and return. I recall that the per person fare for our week was $5200 but we were able to take advantage of a 50% off the second passenger deal. The cruise fare included air fare and excursions. I don't recall that anything on board cost extra. Dom Perignon was the Champagne of choice and unlimited supplies of caviar were on offer on a 24/7 basis. At the time, Cunard operated the two Sea Goddess ships.
Later the Sea Goddess ships were folded into Seabourn after it was acquired by Carnival. The ships were then known as Seabourn Goddess I and II. During the relatively shortlived Seabourn period, the Carnival influence resulted in many changes in the on board offerings such as ditching the Dom Perignon, free flowing caviar, etc. Also during that period, the all-inclusive nature of the experience ended. The most noticeable change was that we had to (gasp!) sign for drinks. That was a relatively short-lived experiment but equally reviled by crew and passengers. In fact, long time Bartender Otto was so incensed by the situation that he quit and retired to Mexico, never to be seen again.
The original Sea Goddess ships were painted primarily white. At one point they were registered in Douglas on the Isle of Man.
By the way, I recognize that none of the above is responsive to your question but since you got me going I figured I'd throw it in. In the SG days, there was no Admiral's Suite. There were a couple of Owner's Suites (215 and 315) but they were nowhere near as swanky as the current Owner's Suite is. I'm not sure why you say there are more passengers now. I believe that the only difference in passenger count is due to the addition of the Admiral's Suite so I guess the maximum capacity has increased by 2. I don't believe that the number of crew has changed materially.
Those who have sailed with me on SD know that I continue to lament the renovation of the public men's room near the Boutique on Deck 3 that resulted in the removal of the urinal. That was in my view a very unwise decision but of course nobody asked me.
As for significant structural changes, I think Deck 2 is pretty much the same. Deck 3 was changed by upgrading the Owner's Suite and either creating or expanding the boutique. Deck 4 now has the Admiral's Suite in place of a small office for the Club Director, a couple of slot machines and a second Blackjack table. The library has been spiffed up. We used to be able to exit the library and go outside on Deck 4 through the doors near the rear of the room. Those are now blocked off to passengers for some reason. The Spa and Gym were added on Deck 4. The Captain's quarters used to be at the front of Deck 4 but were moved to Deck 5 to make room for the Spa and Gym. The Gym (such as it was) was on Deck 5 where the waterfall now is. I believe that it was adjacent to the smokestack. Deck 6 is of course where the most important (to passengers) changes were made. Previously there was a small sitting area with a couple of tables at the rear of Deck 6. The deck area was extended significantly when the TOY Bar was built. There was no golf simulator but instead there was an Astroturf putting green at the front of Deck 6. I have 2 memories of that putting green - (i) it was impossible to read and it seemed as if every time you struck the ball it would take off in a different direction than anticipated or than previously regardless of any movements or positioning of the ship and (ii) on the Alaska trip in 1996 we had a putting contest and somehow I came in second place. Somewhere I even have the certificate to prove it. And no, I have no idea who won or whether there were more than 2 participants :).
So, those are my initial recollections. It was fun revisiting the old days so thanks for the suggestion, Jim. As I mentioned, I welcome additions, corrections, etc. so those who experienced Sea Goddess please feel free to chime in.