Naatkinson says:
It's a group game, so unless something HAS TO be secret I'd rather it not be.
I'm trying to do it more in my other game, but I generally try to stick to a few instances:
1. A player has done a check and noticed something that the others have not.
2. A player does an action that no one else has seen. I do this in case they intentionally did that and want to keep it secret.
3. If only certain people have split off to do something.
The only reason I make those secret is because it's fun to see how their characters relay that information back to their party, or don't. I've seen it often times as well where a rogue character might want to pocket some loot without others knowing so they have their own money reserve they skim off the top.
To me it becomes less of making sure everyone else knows what is going on and more of making sure characters are realistically reacting to situations. It might not seem like a big deal in most cases, but a lot of it can also play into how the characters perceive each other. Your characters may genuinely react differently to someone if they know they just murdered an innocent man in an alleyway only moments before you meet them, or your dislike of a rogue who has pocketed a ton of gems, but said he didn't have money to buy a shortsword he wanted might just feel a little more real if it is later revealed in game that he has been sitting on a stash of money.
Like I said I'm really torn on this though because it's really fun to read the exploits of others, but it can easily steer small decisions of others when they know something that they otherwise shouldn't. If your paladin character knows you just murdered someone in cold blood in an alley only 20 feet away, will he continue on the path he was on, or may he try to incite the conflict by walking towards the alley he would otherwise not have passed?
People say they don't metagame, but we all know we metagame a little bit. Even when I see those little grey note boxes and I'm not included I suddenly become just a little bit suspicious of the names on the box. It's really hard not to when you know secrets are moving around.