I like the Accurite digital humidistats to keep an eye on temp and humidity in my house. They work well and they're cheapish, but they are really designed for plants and not people (the "dry-OK" humidity range is intended for plants.)
I only have the one dehumidifier, though. It goes nonstop in my basement.
Women can get wet sometimes so it is common decency to have a lot of dehumidifiers. If you bring a lady home and she sees your array of 6 dehumidifiers per room, she will be so impressed that she will instantly rip off her clothes and fuck the shit out of you.