I am a big Geddy fan, and have learned a lot of Rush over the years. That being said, Geddy has a very aggressive and somewhat unorthodox technique, and if you are early in your development I would worry about getting the basics down first.
That being said, I would say start with songs like Working Man, Fly By Night, and some of the simpler stuff like Bravado (not a typical Rush tune, but a really good song).
I would then move to say Tom Sawyer, New World Man, and Marathon.
From there, I would work on the rest of Moving Pictures minus YYZ, Spirit of Radio, Freewill, Natural Science, and La Villa Strangiato.
Then YYZ. It is one of the greatest bass songs ever, and it is really tough to play correctly.
Another thing about playing Rush, and playing everything correctly/note for note. Geddy is great, but Geddy really plays a lot of notes. He is occasionally a bit sloppy, but it goes by really quick so between the duration and it sitting in the mix you would not notice. My point is that if you play a song exactly like Geddy some folks are going to look at you like you are nuts as a lot of folks will never notice just how insanely active Geddy is.