Whenever I play for domination, there comes the moment when a pile of GGs is rotting away in my capital, and I can't be assed to make their improvement at all.
The happiness from the GA is always welcome however.
This surprises me! In a domination game, don't you run up against the

unit Supply Cap regularly? I don't think I would ever mind having a spare GG around to steal land from neighbors, nabbing Natural Wonders or spare resources to establish Monopolies. And personally (as a pretty peacable player), I find that spamming Citadels greatly helps (or at least speeds up) conquest.
I'm guessing
Happiness is often the bottleneck to conquest if you're a dedicated warmonger, then? Maybe what we need is a GAdm boost for peace-niks then, since warmongers get good use out of the Voyage of Discovery already.
Two free luxuries leads to (on average) ~+7 GPT and ~+1 happiness for the rest of the game. I would not dismiss that.
G
Thanks for the reply, G!
7

/turn is OK for most of the game but often not very significant by turn 200 or so, IMO. 1–2

Happiness might be pretty significant for warmongers but not so much for peacemongers.
How about a quick and dirty peace-oriented addition to Voyage of Discovery?
e.g.,
+3
Culture per active
Trade Route, scaling with era. (Thematically/historically, Great Admirals are those who paved the way for new, profitable trade routes).

Tourism could work instead, too. And maybe restrict to International Trade Routes, for flavor.