We just finished sheetrock and the first coat of paint.

Calculate the price to rent ratios for each neighborhood if you can.Then most of the work will come from picking the best property with the (best bedrooms/bath split or unit split) to increase the rents.It will be difficult, I am not going to sugar coat it.

Cory Tuck we used to use cinderblocks covered with a scratch coat.

The thicker click together version at HD is 100% waterproof and gets good reviews on these forums.

I agree more curb appeal would come from a paint job, but if newer paint, I would just clean (maybe tsp and light bleach) on half with T-1 11 siding in the photo--maybe the weather side, and roll it out the same color, a fresh coat (or primer, like a fresh start primer, if stained). 

It has older asphalt shingles that I'm hoping will last another 3-5 years before I put stone-coated steel on.

A little fine grit sanding and a coat with a finishing roller and I should be about done with the painting.

A few coats of paint, some open windows and some air fresheners did their best to further reduce the odors.  

The answer is, like most things, yes and no.Yes, thicker drywall can help, which is why quite rock works, but not why you may think.

But it was never ACTUALLY enamel.With the death of oil-based paint for interior painting, paint companies have tried to produce similar water-based paints that dry to a hard, glossy coating that they also (misleadingly) call enamels.Paint manufacturers have also been able to greatly expand sheen levels in water-based paint.