It almost seems like a solid project management type software would be a good target here. I would also say, if it were me I may stick with the excel spreadsheet and then maybe just create individual photo albums for each property (presuming you're taking all these pics with your phone), or if you're using a separate camera, just export them into a folder for each property. Its decidedly low tech, but would require very little startup effort.
I've done this before (albeit 10 years ago) and that's essentially how we managed the process.