She moved into a unit and complained about the noise from the student who lived above her. 

They’ve been talked to about the noise issue before but don’t seem to care.

She was staring daggers at me, making noises at me, yelling, that sort of stuff. 

I currently have a tenant residing in the lower lever, and am considering getting carpet in the rooms above the tenant to deaden the sound (footsteps, loud noises, etc.)Would you recommend carpeting over the hardwood?

It may be that noise transfers easily through the units.

We don't allow dogs in our upstairs apartment above our commercial building because the flooring is hardwood and it causes way too much noise.

Keep giving them 3 day notices to quit making noise or whatever else you can think of that would be legal and related to what they're doing and that violates your lease. 

My signal-to-noise ratio coming from Zillow et al. is not good.  

You have to follow certain code requirements, such as :you can't house more than five unrelated individuals at a timeyou have to abide by all noise ordinances and parking ordinancesyou cannot serve breakfast or else you fall under the B&B lawsTo the question I would have and I imagine others have, Can you buy a property down there and rent it full-time?

How about when family comes to stay for two weeks and you get complaints about noise?