You are right that the range is wide. You need to figure what are good values to have for your category. Also, you can focus on the trend (is your DAU/MAU increasing vs decreasing after you make changes) even if benchmarking is tough.
Unless your app is adding a huge number of users every day (which can skew DAU/MAU), you can trust the ratio as a good indication of how engaged your users are.
For games, DAU/MAU of ~20-30% is considered to be pretty good.
For social apps, like a messenger app, a successful one would have a DAU/MAU closer to 50%.
In general most apps struggle to get to DAU/MAU of 20% or more.
Make sure you have the right definition of who is an active user for your app, and get a good sense of what % of users are actually using your app every day.
Happy to discuss what is a good benchmark for your specific app depending on what it does.
There is no one "good" DAU/MAU number, they vary a lot: is the app paid or free? Is it free with ads or free with IAPs (or maybe no monetization whatsoever)? Is it a game or something else? Some games/apps with low DAUs (in tens of thousands) make more money than much bigger competitors so you really need to focus on specifics of your app. Let me know if you can share more details of your app...
This is the wrong question to ask its like asking how much revenue is good. The more the better.
In general i would place a value of $.25 to $.75 in potential revenue on single MAU on average. However this varies based on the 3 levers which are: # of MAU, length of session, and frequency. It also varies on the type of monetization and app type ie in app purchase vs ads, games vs utilities. etc.
Another interesting thing we're seeing on apptopia now is people buying up android apps with large install base, but low engagement i.e. utilities. As it turns out you can monetize the apps with certain ad networks that install some addons to the phone and display ads outside the app or through push notification. Some examples: Pingjam for caller id ads, Airpush for push notification ads,StartApp and many more. At some point Google will catch up and block these networks but as of right now its a wild wild west out there....
hope this helps.