Best way to manage multiple Wordpress sites? Hope for a better way...

Has anyone found a good method of dealing with multiple Wordpress installations? Logging into each one individually when a new version came out was okay with a dozen or so. I now have gone over a hundred sites across the three hosts and keep building more. Things like upgrades and plugins are getting difficult to handle. Backups are a nightmare. Trying to keep track of site design specifics, SQL database names and users, and alternative logins is filling up Excel spreadsheets.

To be honest, I never learned WPMU as it didn't seem to apply to what I was doing. Perhaps that is an answer? Does anyone here have any experience using WP ManagerDX I don't like that it is an online service with an annual subscription fee, so I'm hoping there's something better.

I would prefer a program installed on my computer, and am also looking at WPDesktop which seems a better fit. Does anyone have any experience using this program? If so, do you like it? It seems almost too inexpensive.

My first attempt at dealing with the large number of logins was to buy a copy of RoboForm. It has made life a lot easier when using passwords, but things have gotten to the point of having to print out a checklist to do updates to not lose my place.

Are there any tools or tricks or ideas you can suggest other than these? I know there has to be a better way - an easier way.

Thanks, Ken