I would ask the electrician to verify that the rest of the house is up to code, as replacing the panel may open you up to having to do other stuff as well -- like GFCI in the kitchen/bathrooms, etc. 

If you wish you may stipulate a occasional visit by a handyman to assess the condition/perform landscaping/ appliance maintenance, and note any noticeable negative changes to the condition, to make sure the property is kept.

In my market, and most of the northeast, appliances are de facto the responsibility of the landlord

In terms of what I think it needs to rent stronger would be, new interior doors, facelift the kitchens, appliances are good and new interior paint.

You find that out when you go to show the unit when they never asked permission to paint even if it's in the lease.We used a set color, Antique White, Contractors grade Conco brand from Menards. so we can touch up after move outs and never have to think about "what color was on that wall" I use a eggshell finish on everything except kitchen and bath. there I use semigloss.So pick your color and 5 gallon buckets are best cost savings. 

The total rehab needs no more than 40k (interior needs lots of work, kitchen and 2 bathrooms will be full gut, the rest is cosmetic with some drywall replacement) to really make it shine and stand out from competition.The asking price is $87,000.  

I’ve made some upgrades to my unit: new AC, hurricane shutters, bamboo flooring, as examples over the years, but haven’t upgraded the cabinets, countertops, or tile in the kitchen or bathrooms.

Also, repairing washers and dryers can be very costly, sometimes as much as a new appliance.

Project scope: landscaping, new fence, new plumbing (from the main and in the house), new electrical, converted from oil to gas, new HVAC, water heater, reconfigured upstairs to include 2 BRs and a real full bath, gutted kitchen, new bathroom on 1st floor, refinished HW floor, new roof and gutters, repair fascia, soffits, siding, painting, concrete work on sidewalk and driveway, new basement windows, new door and windows on detached garage.

He placed appliances in the house and says he wants to be paid.