+happy loses none of its luster once Monarchy hits.
The warrior costs 15h and, on Monarch, costs .7g/t to maintain.
An estimate of the present value of .7g/t is something like .7*42=30h
Over time, it's as if you paid 45h for that happy. That's a lot. Certainly, some of the value of +3 happy comes from the time before Monarchy when other civs might be more constrained. Given that HR happiness is so expensive, however, much of the value of +happy is independent of Monarchy tech.
The warrior costs 15h and, on Monarch, costs .7g/t to maintain.
An estimate of the present value of .7g/t is something like .7*42=30h
Over time, it's as if you paid 45h for that happy. That's a lot. Certainly, some of the value of +3 happy comes from the time before Monarchy when other civs might be more constrained. Given that HR happiness is so expensive, however, much of the value of +happy is independent of Monarchy tech.