I had one on my house for the first year (realtor gift, American Home Shield) and it was great.

Quick Question: I was gifted a rental property which had a tenant and lease inplace.

Gift your parents a down payment if you want to help them.  

Possible strategies include first and second mortgages, joint venture, mezzanine loans, seller contributions, and gifts of equity.

I like Starbucks gift cards... :)

We treat these people well with tips and extras like gift cards.I have another gentleman that powerwashes driveways, decks, siding etc.

Gift certificate to his favorite golf pro shop.

I.e if you are in a place with long, cold winters and where the norm is to construct {residential} properties with full basements, then an uninsulated, yet conditioned, basement could be the source of 20+% of your heat loss.Dustin - a 3.5" air gap may be reasonable in Kansas (if you wall assembly was air tight ... even then I am doubtful) - however, it does nothing about the 12 - 15% of your wall that is framing and a thermal bridge.When it comes to windows, there are advantages to triple glazing and inert gases (though they do eventually normalize with the atmosphere) ... however a well-built double glazed window with an insulated frame will match, or out perform a triple glazed window with your run-of-the-mill aluminium or vinyl frame.   

It really is the gift that keeps on giving.

I would likely give them a break in the form of a gift card to a decent restaurant.