The thicker concrete on the outside helps carry the weight, but really doesn't do much more.

You'll then have many more years of income without any upkeep worries. 

Finding a property management company that you can trust with your investment can be a weight off of your shoulders and provide "mailbox" money to you without you having to lift a finger (except for when you have to grab that money from the mailbox).The cost of property management services varies, but any great trustworthy property management company can outweigh the cost substantially by providing you with time-saving services that handle the day-to-day operations of owning a rental investment property.

A "good" tenant can be worth their weight in gold! 

In my case, most of my close friends are what I would instead call middle-class to upper-middle class.They work well-paid jobs (mostly in the tech industry) and make very respectable salaries, but...that income is in all these people's cases frittered away on paying for the upkeep of an expensive home in an expensive neighborhood, multiple late-model cars, and bad investments (most typically actively-managed target-end-date pension funds with high expense ratios).I have three millionaire friends and family from this pool of friends, all people who made their money investing in small businesses.

So I would make sure you keep your eyes open for pitfalls when absorbing other peoples teachings/wisdom, even mine, or especially mine :)  Go do your own homework, find other opinions and weight their ideas by their merit.

Hi Apurva,53 units -- It would be smart to talk to an Architect who does multi-family (In your general area) about the cost of doing a restyle as well as colors.Especially if you choose a Hardie (Fiber Cement type) product.With Hardie (Type) products, read the upkeep instructions, some require re-applying the joint sealers (factor that into your maintenance budget).Also with Hardie (Type) products there is a service life to the color...some come pre-colored, some your contractors must paint on site, (some require priming of cuts when installed)---talk to the Architect about the maintenance schedule and the CAPEX for this.Hardie makes big sheets of this for multi-family that Architects can use for visual effect and ease of installation.With 53 units--springing for an Architect to help with this would be intelligent.Good Luck!

Get a builder quote from at least 3 LOCAL builders or Renovation Contractors first, then weight your available options. 

Do you have a weight limit on dogs to keep the potential "dangerous" breeds away, or do you find that most folks don't travel with their 100 lb Rotty?

They don't want it, it is literally a problem that will cost them money every year in taxes and upkeep.