Bobcat, I think you're on the right track. I will not rule out that it could be resurrected humans, the information is somewhat scanty. But here's what TDNT has to say, along the lines of what you are suggesting. They seem to be God's council of elders. The fact that they do not participate in the judicial process in the book of Revelation doesn't mean much. It could be that we do not have all the information:
4. The 24 πρεσβ?τεροι in Revelation. Special problems are raised by the passages in Rev. in which, in the visions of the divine, 24 elders surround the throne of God in heaven along with the four beasts, 4:4, 10; 5:6, 8, 11, 14; 7:11; 11:16; 14:3; 19:4. 99 The thrones on which they sit (4:4; 11:16), the white robes and the crowns which adorn them (4:4), show that they are heavenly beings, and the title πρεσβ?τεροι suggests that they are God’s council of elders. Yet there is no mention of God sitting in council with them nor do they seem to discharge a judicial office, cf. 20:4. Their function is not the exercising of their own dominion; it is simply adoration of the majesty of Him who sits on the throne (4:10; 19:4) and of the exalted Lamb (5:8–10) → θρ?νος , III, 165, 21 ff. They sink to the ground, offer worship, and cast down their crowns before the throne of the eternal and omnipotent God (4:10) with songs of praise (4:11; 5:9 f.; 11:17 f.; 19:4 etc.). According to 5:8 they offer priestly ministry for the earthly community with harps and golden vials. Their divine service in heaven accompanies the events of redemption and judgment on earth, which the elders inaugurate and conclude with gesture and song.
There is no suggestion that these elders are redeemed and transfigured men. 100 They are plainly differentiated from the transfigured, 7 and 14. They are also distinguished from the angelic hosts (5:11; 7:11) which surround the throne, the four beasts and the 24 elders. But they are so only as a higher class of angels which is closer to the throne of God than the others and which is entrusted in a peculiar way with His secrets. “One of the elders” functions as angelus interpres (5:5; 7:13) and the seer addresses him by the title of majesty, κ?ριος , 7:14. See TDNT, vol. VI, p. 668.
99 Cf. Michl, who carefully surveys the history of interpretation.
100 The thesis of Michl, 91–114 that the elders are the righteous of the old covenant viewed as the heavenly presbyters of the Chr. people seems to me to be quite untenable.