ADDED: This question is now, I believe, subsumed by this one: Using GNU Screen completely transparently and automatically
See also this related question: https://s
If you like to connect to the same session always even it is active, detached or not exists yet:
ssh -t user@server screen -xR screenName
The same but create a new session if it is already active on some other pty:
ssh -t user@server screen -rR screenName