Do you attach your map to the bike or have some sort of desktop or how do you maintain your map during touring? You surely need some sort of cover but if you have how do you attach it to your bike or do you keep it in your pocket? Exploring different ways for maps, seen some pannier-attached map things but there are surely many other. Experiences?
Doesn't address your question with regard to maps, but I've found it easier to work from turn-by-turn cue sheets instead. I almost always ride a predetermined route, even if it's just something quickly charted up pre ride. Luxury is of course having access to google maps and being able to print out directions. I print out (or write out, sometimes you have to fall back to the basics) the text list of turns with cumulative mileage (most important!) as a cue sheet, then just clip it to my shifter cables with 3 or so binder clips. You'd think the wind would be a problem but I've done it hundreds of miles and never had an issue.
When you get lost, or the plan changes (it inevitably does) we'll stop and break out the map and come up with an updated plan and turn schedule.
I find this way much more enjoyable because you can relax between turns knowing when and where to look out for what's next.
I have seen some handlebar bags that have a slot for maps on the top. The map pocket is usually clear plastic designed to keep the map dry. (Hopefully this isn't what you meant by "pannier-attached map things" -- I have never heard of/seen those; maybe you were thinking handlebar bags?)
There are lots of bags that have this (Google "handlebar bag map pocket" if you want to check them out). Here is an example.
The best solution: Have a navigator with you, who has a handlebar bag with a map sleeve:
Otherwise I almost always ride with a handlebar bag, which has a transparent map sleeve on top. Both options on the same picture:
Two maps possible, in case you want to go different routes
On trips without handlebar bag, but with low rider panniers, I have used a clear Ortlieb map case strapped on top of one of the low rider panniers. For me it is possible to read the important details on the map even at this distance, at least on smooth roads.
I had some of my most interesting days on the road when I deliberately rode home from almost 1000 km away, through an area where I mostly had not been before, without a map or compass. Only road signs, imagination, common sense and asking people. I should really do that again...
I usually make my map before and upload it on my garmin, i have the same map on my phone via google map in case i need more details (which I keep in my backpocket).
If i don't want to go to a certain location but just want to ride, I let my garmin goes and use the "return home" feature when it start to get late.
Zip tie + Binder Clip on Stem clamping to a 1 Gallon Ziplock Plastic bag with properly folded map inside. Alternatively, if that's not secure enough, use 2 binder clips + zip ties on the handlebars.
I found a similar DIY setup using velcro wire ties
It's usually in my pocket. My long distance riding is often in remote areas, so I find that I usually don't need a map right in front of me since route changes are frequently miles (kilometers) apart. If in a tricky route area perhaps something like this. A map cover could probably be homemade pretty easily if one was so inclined.
Granted this answer is not for everyone, but it is simple for tandem riders. As the helmsman/captain I wear a Camelbak with elastic webbing which holds the OS map conveniently in front of the stoker (I have a photo somewhere). I get funny looks when I walk into shops with a map on my back, though.
If the scale is large enough it can be read while pedalling, although I'm sometimes told to keep still so gradient lines can be read.
On my tour across the US, I bought a statewide gazetteer at a gas station whenever I entered a new state, and then threw away all the pages that I wasn't planning on going through. I kept the rest in a pannier, inside a large ziplock freezer bag to keep them dry.
Whenever I stopped for a snack (about every couple of hours), I'd pull out the page where I was and look ahead for the next couple hours -- usually this would only be a few turns to remember (or none, in Montana). At dinner I would pore over the map from that day and for the next day to regroup mentally and plan for what was coming up.
It probably depends on your comfort level with your "sense of direction" and where you are touring, but in most places without a ton of roads it's surprisingly easy to find your way around -- you just take the road that heads west/north/whatever.
I had the older version of this Vaude Discover Box for long touring and found it indispensable:
I always had a map in the map pocket and kept all the stuff I needed ready access to in the bag/box i.e. wallet, camera, snacks, etc. It opens from the rider side so you can access it on the move and it unclips so you can take it with you when you stop.