I rarely use the drop down menus for Characters and Games and I probably won't use the drop down menu for Forums. But I'm not opposed to them either. I can see why some people like them.
However, I love the bookmarks idea! I feel like it would be a good replacement for the drop downs.
The way I would like to see bookmarks implemented would be a new Bookmarks header (which maybe has a little arrow to indicate it has a drop down). The first link in the drop down list is the link to a My Bookmarks page, which is a page with two lists.
1) gp urls that you want in the Bookmarks drop down that would populate under the first link which is reserved for My Bookmarks.
2) gp urls that you don't want in the drop down, but you want to save for reference on the My Bookmarks page.
There should be some buttons to easily rearrange the lists (e.g. move up, move down, move to top, move to bottom, move to position __#__, delete bookmark, etc.), so you can organize the order however you like.
You should be able to manually copy urls into the lists. And on each GP page (regardless of type, so on a game details page, or a character page, or a forum, or a thread, or a post, etc) there should be a bookmark button that if you click, it copies the current url into your list (maybe sort of like the subscribe button).
With this new Bookmarks drop down, I would guess the other drop downs would be redundant, so I'd remove the drop downs from the other headers (Characters, Games, Forum) and instead they would just be links to the relevant pages (My Characters, My Games, and Forum).
For new members, I would auto-populate the Bookmarks drop down with Introductions, Guides, Questions and Help, and Games Tavern.
I think this would improve site navigation.