I've never tried a family for that but I think goups are more appropiated, works for me perfectly including tags and schedules.

 PZ explained it well...you don't want to use families.  Only thing I considered using families for related to multi-family residential is the kitchens.  You could, hypothetically, nest all the kitchen components into a singe family.  Benefit could be that you can use a legend for your kitchen type elevations, instead of having to elevate them with actual tags and then deal with tracking how that elevation may move around if you scoot the kitchen stuff one direction or another.

We had this problem on a few projects, and I think this could be a good way to deal with it.  Typically, our kitchen type elevations only display the kitchen with no surrounding context.  We have also sometimes show an elevation of the wall(s) the kitchen is on, for context, and then just block out the kitchen with thick dashed lines and refer to a larger, more specific kitchen elevation that has all the annotation, etc. on it.  

I haven't tried using a family for the entire kitchen on an actual project, so I am not sure what negative consequences may be related to doing it this way, but it seems like it could work well.

IMO creating separate "Unit" links is not the way to go.  Files can be: ovewritten, renamed, deleted, moved, repathed, ect. Then there's duplicate files all over the folders & no-one can identify which one is most accurate. AND the link often gets placed inncorrectly in the model, one on top of another or on a different level than was intended OR on the wrong workset. 

Then there's the nightmare of updating families within all these separate Unit files.  Say you need to update a door type, you would have to open each of the Unit files & reload the family you've updated - that could take hours, whereas if you created Unit groups, it would be done in minutes, since ALL the groups will update at once.

While we're on the subject of units - I recommend that any plans that are distributed for review & markups be oriented the same as the original instance in the model. So if in the model the entry door is to the right, the plans that get printed should have the door to the right- that way it doesn't require studying a mirrored or flipped print to see if I've got the door swing correctl, or have updated the vanity.  It's just a time & aggravation saver & should be a standard practice.

Happy Reviteering!