Ubuntu – Server AMI images don’t allow a user to login multiple times

I think you're asking how you can shorten the following command:

ssh -i ~/path/to/your/ssh_key.pem \
   ubuntu@ec2-79-125-64-190.eu-west-1.compute.amazonaws.com

That can be accomplished with with edits to ~/.ssh/config. The following example ssh config stanza might be helpful:

Host myec2server
  IdentityFile /home/USERNAME/ec2/ec2-keypair.eu-west-1.pem
  User ubuntu
  HostName ec2-79-125-64-190.eu-west-1.compute.amazonaws.com 

Now, you can just type ssh myec2server. see man ssh_config for more ssh_config tricks. You can then combine that with another of the answers here and create a launcher with the command:

gnome-terminal --execute ssh myec2server  

Also related, is a new-ish EC2 feature import-keypair that allows you to upload your own public keys. Then, you can launch new servers with keypairs that you use elsewhere.

Unfortunately, the 11.10 AMIs automatically run the screen command on ssh from a terminal using a package named byobu which uses up the bottom two lines with colorful line noise.

You can disable this on a given instance by typing the command:

byobu-disable

which will log you out. The next ssh will work fine.

Note: This post includes statements that express my personal opinions. Other people have different opinions.