Usually, just having an inspection contingency will save you from any real material issues.

I couldn't have done this without the bigger pockets community, and supplemental materials provided to me by this site and its members.

(But cheaper than a college degree and probably worth more.)Most contractors love T&M (time and materials) projects because you take all the risk.

You are spending a lot of time wondering if you should invest an extra $50 on higher quality materials.

Labor and materials go up. 

In your experiences, did you find a default set of updates that you like to do with all your properties, such as a certain look or material in your kitchen?

Wood or is vinyl the original material?

But if you need to rent one and document results.You might look into some sound dampening material as well.Before doing all of this, in a non threatening way, best you can - try to develop a relationship with the neighbor so that you don't have to go down the civil adversarial road.....

You can get material to soften the sound of footsteps as well underneath it.Those stores you mentioned should be able to do the job for you

In addition to quality of materials, you want to appeal to the largest group of people possible.