Maybe this have already been suggested but here goes:
1) Problem: Server Busy and constantly having to retry logging in. This also taxes the authentication process.
Solution: Provide a Queue. This will prevent extra authentication calls as well as give a visual on place in line.
2) Problem: When disconnect and trying to relog on within a very short time, you have to fight with everyone else to get back on.
Solution: Give a few minutes of protection and saving someone's spot on the server giving them a chance to get back into the game.
If you wanne change your character you have to logoff as well, and then you cant login due to the server-cap. Maybe an option to change character without loggin off would be nice.