I’ve been goal oriented and driven my entire life in one form or another.

You're so nearby, have you come up and driven around it yet?

Should this just be a standard, vanilla "This formal notice....blah blah...I will not be renewing our Lease Agreement...sincerely, landlord", or should it just be a "I, <tenant sign here>, have been notified that the Lease Agreement will not be renewed and will vacate the property by xxxx, 2018"Am I just really overthinking this? 

Our money is consumed in the downpayments, and that's the end of our REI path.If I could do it all again, a) I would use the BRRRR approach over and over to maximize my available investing funds, and b) I wouldn't mess around with single family rentals but focus instead on commercial multi family.Hope there's a nugget or two in there. 

She's leans a little to the more emotionally driven (think Sonny).

Take advantage of the spread.The only reasons I wouldn't do this are (A) I have other properties that I want to save my DTI for or (B) I don't have enough W2 or other income to cover the $400/month in a worst case scenario or (C) I can't find any safe investments that will yield me 5%+ or (D) The closing costs for the refi are high.

Generally many jobs will disappear and some will be new jobs due to many technologies...Internet of Things (IoT)Virtual realityAugmented realityDronesBig Data3D printingRobotizationArtificial Intelligence (AI) andMachine LearningBlockchainData Virtualizationand we will all work in smart cities, smart buildings, and deal with home automation...get ready!

The value of SFHs is driven by home owners not investors or tenants.

Since it does not sound like you are a driven investor and you are trying to make a decision between personal and investing there are many reasons why you would be best to sell.

Based on the numbers alone, I'd say it's not a great deal but would be marginal If it's in an area where you could expect some appreciation, market driven or forced, and get out of the PMI payment.