Gifting an Expense Tracking Tool

[Peter Macron]

Hey guys! Since I was a little kid my parents have been flipping houses on the side and some of my earliest memories consist of sitting on the floor of some random house while my parents painted the walls. I recently graduated college - paid for by the houses my parents were flipping while I was off studying - and wanted to find a modest way to give back what I could.

To do this, I'm making a tool that lets them scan their receipts and it will automatically upload it to a pre-formatted Google Sheet that they can keep for each property to track expenses and eventually other metrics like returns etc... The first prototype is just about complete, all I need to do is set up an inbox/drive for them to send receipts to.

I'm posting here because I wanted to ask what features I can include to make this tool even better for them and make it a more special gift. I know talking to them is a great way to do this, but I want it to be somewhat of a surprise. Currently, they track their expenses by keeping all their receipts and invoices in a physical book that they hand to our accountant at the end of the year (poor guy, lol). 

So, what features do you think I should add? Do you think this is a good idea at all? I know Quickbooks exists, but I wanted to make a tailored solution for their needs rather than just purchase some software for them to use. What are some good references for looking at how people set up their spreadsheets to track expenses? My background is in math and engineering so I also think it'd be cool to analyze their spending and maybe start recognizing areas for improvements. 

Any help is appreciated. I owe them more than I can list here so I want to make this special. Thanks.