Given a choice, I will take an open field or prairie over timber anyday.
I came from calling the wide open prairies of the west to the timber country of the midwest. I found out very quickly just how much different it is.
The coyotes themselves are not any smarter between the two regions, but the midwestern coyotes have the clear advantage over hunters. A coyote in the timber can circle around you and you have no clue they were even there. I have witnessed this many times with coyote tracks over top of my own footprints.
If you have a situation and the wind allows it, set up in the open and call into the woods. Try to make the coyote come into the open if at all possible.
Another tactic to use in the woods is to use an elevated position such as a treestand.
A few years ago, a friend and I sat in a big box blind up in the trees. The blind allowed us to see a lot farther and it also allowed for the calling sound to travel farther. We did have a coyote come into the call on this stand, but it dropped into a ravine but never came to where we could get a shot.
Another favorite area of mine is open marshes when the water is frozen. The coyotes will use the ice as travelways and will usually present themselves in the open for a shot.