I finally got my ipad (wifi only) to show its proper location by doing a combination of some of the above suggestons.
I had good positions on my ipad for quite a long time, but had recently lost ANY location while at home on my wi-fi. Find my phone was saying the iPad was online, but no location available. Also, had good locations for it at other peoples homes while logged onto their wi-fi's. So... First, to make sure my router was properly located, I turned off cellular and Wi-Fi on my iPhone, and I went outside (for good GPS coverage) near a window near the router. Then went to maps to get my location. At first the circle of error was large (several hundred feet), then slowley (over a minute or so) narrowed down to very small. I let it wander a little for a few minutes. Then I turned on Wi-Fi, selected my router, and selected "Forget this network". Waited a minute or so watching my position in Maps (Maps was on throughout this process by the way). Then I reselected my router in Wi-Fi again and typed in the password. Maps was showing a very small circle of error. Next, to check it out (still on my iPhone) I went to airplane mode (to turn off cellular and gps) and turned Wi-Fi on. Now I should only be in wi-fi for locating myself. Went back to maps and had a large circle of error (maybe 600 feet or so) but it slowly went to a small circle (less than 50 ft) within a minute or so as I walked around the yard near my window. Went to find my phone but it still said my ipad was online but no location available. Went to the iPad and did what Chris Innanen said above, which was to - on the iPad, turn off wifi and location services. Went to maps and drew a blank as expected. Turned back on wi-fi and location services (I think in that order) and got a proper location in Maps, centered on the location where I had established with my iphone for my router. The circle of error was about 600 ft, (while at the same time my circle on my iphone was only about 20 ft). This whole process was done in about 20 minutes time, so I didn't need a half day to two days to get things on track. My ipad circle of error was down to about 500 ft after an hour or so. When my wife comes home I am going to do the same thing with her iphone to see if it gives my ipad location better confidence (smaller circle). Another ipad in my house gives me the exact picture in Maps as my first. Same center of the dot and same size of circle.
I later tried another ipad in the house, but when I turned on maps, it told me something like "turning on frequent places will improve locations etc,etc", so I wonder if that may have something with the crowd based data. There is also a switch next to that (all under location services) titled "Improve Maps" which lets apple use your frequent places for better map locations. Hmmmmmm.
Update while I am writing this, the ipad error circle has grown a bit back to about 600 ft, yet I have done nothing else in between. I will definitely be watching this over time. !!
Hope this helps someone else.