So many great thoughts and advice - thanks everyone! (Even those who hadn't yet had their coffee - @Jon Crosby!)
I must say that my question was far more narrowly described than the scope of the actual project, which in reality is a new-build "anchor" house for an agrihood development. My parents live on a small farm just outside this university town and have transformed it from a run-down place into a beautiful, organic veg-growing hub for community/regional events (weddings, reunions, etc.). The longer term vision is to develop the farm into a well-designed agrihood but this new-build would be the "main house" while agrihood plans get drawn up.
We're totally missing out on great income (and the added marketing opportunities for the farm itself) by not currently having on-farm STRs for all the visitors to the farm, much less those coming to university events during the year. So this is where my original question comes from. The concept at this stage - now that my parents are ready to downsize - is to build what would essentially be a 4-plex, with three of the units being STRs and one - my parent's - as more normal sized main floor and upstairs.
Likely clients will indeed be parents/families in town for university events, visiting academics and artists, tourists, etc.
@Julie McCoy - your comments about closets and kitchen storage space are spot on. Hadn't yet even got to that level of detail yet - but I absolutely have done so now!
@Paul Kessenich - absolutely, this place definitely needs to be more "homey" than "hotel-y." It sounds like we very much have the same target clients. I think long weekend-ers will be my bread and butter, but I'd like to attract weekly or monthly tenants as well, so the more comfortable, the better.
@Andrew Johnson - excellent advice for me. I've always had a pretty good idea of who likely clients would be, but I think it would be valuable to really give it some more thought and put together a written profile of the most likely tenants and think about plans from their vantage point.
@Bill Cereske - very helpful input. The vision of my parent's farm is very much organic, eco-concious, natural materials, etc. We're already planning for this place to be passive, if at all possible.