In general I agree with Dave; mostly on-road tour, go with the Randonee / more off-road, go with the Safari.
However, there's also the personal preference aspect. If either of you prefers a hybrid-ish style bar, that could push you towards the Safari. With slick tires, it can roll 90% as well on pavement with higher tire pressure, and the fatter tires of the Safari will let you drop the pressure a bit and soak up some nasty road shocks (like old concrete roads from Missouri west). Heck, try them both out and buy the one you ilke better!
Either way, tell the mechanics at REI what you're going to be doing with the bike, and ask them to check it over thoroughly. I've had new wheels on a Randonnee start breaking spokes within 1,000 miles, and another set of wheels that they checked over now has over 12,000 miles with no broken spokes (that I can remember).