If you can develop a reputation as someone who brings in high quality deals, you'll make a fortune. 

Don't think I would do it while it's actively being rented due to the unforeseen complications with your lease agreement, although once you do make your improvements focus on quality, which will allow you to ask a higher rental rate and will as a by product help with your screening process and hopefully attract a better tenant which should ultimately increase your ROI.

I'm currently deployed in Kabul Afghanistan in the dirtiest, nastiest air quality in the world and we get some pretty crazy dust storms out here at times.

That would still cause your bill to blow sky high, but might honestly be imperceptible to your tenant.If you spend $5 on a flapper, instead of $13 for a better quality part...or spend $100 on a toilet (which has a $3 flapper inside it) instead of $250 on a better quality toilet with better quality parts inside it...be prepared for this to happen again in the near future.

I was never sure if I just had high standards because of my architecture background, or if indeed, my contractors were performing low quality work.

I had an open house and got 5 GOOD quality choices for tenants.  

I am planning to put 2 smart locks (probably Kwikset 916 - I do think the Schlage is better quality, but I like being able to rekey myself).

Specifically, found a home that I think is a good deal and maybe eventually a good sell opportunity - with a little TLC of course. 

We are using a flooring vendor to replace some of the low quality carpet with vinyl flooring in the bedrooms.

Not sure if these numbers would work in your current area, but you probably want to own in an appealing area for other tech workers to ensure you're getting quality tenants as well as live in an area you like and enjoy yourself.