The room we have booked now is 4E. Even though it's coded as a larger Family cabin, the interior is actually the smaller layout which only sleeps 4 (no extra space + Murphy.) But it does have the verandah which is 2-3x the normal size, including two lounge chairs or half loungers.Have you considered booking an inside cabin instead of a family cabin and just a regular balcony cabin? If you're not sleeping with all four of you in one cabin, you may not need the larger family cabin size, and it could reduce that extra $1,500 a bit.
If we switched to a 5A (standard cabin with the normal verandah) it's literally only $100 cheaper on the same deck. The absolute most we could save would be about $250 if we went with a lower deck and/or undersized or obstructed verandah. At the end of the day, the upper floor extended verandah is worth that money for 7 nights. We've had these cabins before, and it's a great place to unwind without the hustle and bustle of the pool deck, eat a meal in peace, etc.