I'm from the madison area as well and had a similar problem with my girlfriend. I ride mainly for exercise on the weekends and was becoming frustrated that she never wanted to go on long rides or would always stop. I got her to do the full capitol city loop (about 15 mi) and she wouldn't go with me for a while after that. My solution was to do my long "exercise" rides when she was busy, so when she wanted to go, I could feel at ease taking things at her pace and taking breaks whenever she wanted. Also, I found out a big part of her reluctance was a fear of riding near traffic. So I made sure we stayed on bike paths or bike lanes on less travelled roads at first until she built up her confidence.

In terms of your distance problems, I may be wrong, but I think there are some buses that travel from Madison to oregon and have bike carriers on the front--I may be wrong, but it is worth looking into. All in all, driving a short ten minutes is worth it to get someone interested in the sport--Sometimes the end justify the means--Once she has her endurance and love of cycling built up, maybe she wont mind the long ride home.