I couldn't recommend any 'good' RTS games, cos I hate that genre, but I could advise you to not rely on Steam's Offline mode. Without an internet connection:
- Steam will shaft you.
- Steam will try to phone home.
- Steam will lock you out of your games if it can't phone home (yes, even in 'Offline' Mode)
- There willl be nothing you can do about it until you get a good unrestricted internet connection.
Before you leave, make sure you have cracks for all the Steam games on ur laptop.