I voted for the Current Characters post because often times during 4th wall, seeing a visiting character will spawn me wanting to bring another visiting character in. I did this last year with Rose and ended up apping her. I know it's more work for the mods to pre-approve and I think it discourages impulse visiting characters that might turn out to be permanent residents.
That being said, I will still bring a ton of characters if we choose the other option.
Either way, I would adore anyone who could keep an index maybe of threads, particularly of the visiting characters. It's easy to lose track of who has come to place, particularly if it's a new person who isn't on plurk or ooc planning etc. Again, I know this is a lot of work for the mods, but in this case maybe they could get a helper?