I'd like to get advice from strong go players - let's say amateur 6D+ or pros. What are my options for getting that advice?
I am not necessarily looking for full game reviews, rather comments on one or two turning points in a game.
GoKibitz is a new website that offers a nice frontend for discussing games. I did not use it myself, but it looks promising. I have no experience how strong the players are which are commenting regularly, however I saw at least many 1d or 2d comments.
If you are willing to spend money on getting regular full reviews on your games I can highly recommend In-seong's Yunguseng Dojang. It is available for American and European timezone. You are getting lessons and reviews of league matches from high amateur dan players. I participated in the school myself for 1 year.
As I am new to this site I am not sure if such an advertisement is considered good practice here. Please comment if it isn't. I am not completely sure if the question already is a good fit for the site, because there can be very many answers providing different resources. Selecting one of them as the one right answer is probably not possible.
Join a Go club with strong players. Your club mates will give you comments and hints. Visit Go conventions and go to Go tournaments.
If joining a Go club is not practical for you, consider to take some payed Go lessons by a professional player.
The Go Teaching Ladder is a good place to get comments on your games. Unless you're already a dan player, you won't get comments from 6d+ players, but you also don't need them. Your game will be reviewed by a player several stones stronger than you, and they will be able too see enough of your mistakes to help you get stronger.
OGS has a review requests section. I just got a great review there so I'd like to share the link.
Some Go tournaments will feature professional commentators who will also play several "simultaneous" games with players, typically for a small fee, such as $10 or $20 a head. They will remember the salient points of those games and point out the most egregious errors.
These professional commentators also observe and comment on games, but typically only if you are 1-2 dan or higher.