This morning my in-laws came with us to church. Needless to say, it was quite a change of scenery for them. They didn't really ask too many questions about the architecture, or even the Liturgy, although there was one point when my father-in-law took issue with one of the prayers that entreated the saints to "persuade" God to be present. I tried to explain to him about the poetic liberties sometimes taken in the Liturgy but I'm not sure he found it very convincing. Another point they raised was the repetitive nature of the prayers, both within the Liturgy itself and the fact that its repeated every week, and Jesus' words in Matthew 6:7. I know for my FIL, the main issue was mostly of a pragmatic nature - does the Liturgy do what it should? Does it meet people's needs? My MIL felt the priest's role took on a mediatorial role and that, as believers, we have direct access to the throne so why do we need a priest?
Overall, the experience sparked a lot of questions, probably a few rush-to-judgments on their part, but a good discussion. I tend to doubt that they'll ever be comfortable with Orthodoxy if we decide to convert, but at least they have a better idea where we're coming from.