Thanks for the nice review, TBS.
I'm considering different room type options for this hotel, plus also considering the Orchard Hilton which is the property I'm a lot more familiar with.
I see that you reserved the exec room with hopes for an upgrade to suite, which you did not get. And you were not always able to get into the 31st EL due to capacity issues.
But you also got to enjoy a fantastic view since you'd assured yourself to be amongst the highest floors by booking Exec level room.

What you say that the view alone made booking Exec room still worthwhile?
And, for the hours outside of evening cocktail hours, is there significant difference in the quality of food/beverages/ambiance between the 4th and the 31st floor lounges?

We're only going to spend one night, probably will be at the hotel only from 7.30p-9.30a.
Right now I have us booked into grand deluxe twin which is supposed to be 13th-17th floor, but I'm hoping my Diamond status gets me upgraded to a higher floor although I understand that an upgrade may not happen and that an upgrade does not get me into 31st floor. The Exec Twin room is 120SGD more than Grand Twin, which is a lot. Since we're arriving at the hotel ~7.30pm, the evening cocktail ends at 8pm, and we have kids <12yo, wife and I would only be able to use the 31st EL after the cocktail ends and before the lounge closes. So I guess the view is the more important deciding factor here.

Singapore Hilton is 70SGD less... I know that Conrad is more upscale, but I love the staff there and its Orchard location. Main reason I'm so far choosing Conrad over Hilton is that it's a bit closer to the airport.