You're right about scores. Most of mine are in the 15000-25000 bracket. Domination & conquest usually score higher, into the 30000-40000, and cultural wins lower because I'm not very good at them.Anyway, as long as I enjoy the game I won't worry about the score.
most of my games, including cultural, are between 30k and 40k.
That's a question of population and finish time, mostly.
But my "best" games are usually much lower. Because what I see as best are those unusual games, where you have to find a way out of the hole.
Sometimes those can give a quite high score (I remember my fist monarch game with warlords, playing churchill. I started on a remote peninsula, with very little quality land. I abused the vassal system, in some very british way. 4 vassals, = stallin, mansa musa, alexander and J Caesar gave me a high enough score),
but mostly, you need to draft, whip (= lose population)
and give up on wonders and techs (building and paying for troops, pushing the cultural slider to remain happy=no time for wonders and no commerce for science) to win those.
10K is high enough when the game was good.