Hey new climber,
I think you should go for the 150 foot/ 50 foot lanyard option. Get your gal a 150 foot rope too. You'll have hell to pay if you leave her grounded while you monkey around. Get it?
What kind of training do you have? Get TCI'd $20 DVD and you and your girl can learn together. It's much easier two folks learning together than a solo learn.
Where you at? What kind of trees you got. Tell us here. Hey, there might be a climbing partner right around the corner. So introduce yourself here if you haven't already.
Cheers
Treeman
Waving from a treetop,
Peter Treeman Jenkins