I feel for her...
I think there are two things worth aiming for, and you might well not find them in the same activity. It would be good to find her something that she really enjoys; and it would be good to find her something she can do enough, regularly enough, to maintain a high enough level of strength and cardiovascular fitness that, even if she isn't very skilled in the team games she does, she isn't panting and unable to apply what skill she has.
I think the second is the hard one. A decent level of fitness really takes quite a lot of activity to maintain (at least for some people - I have the impression that some people lose fitness with inactivity much faster than other people, and suspect that this is part of the difference between "sporty" and "unsporty" people, but the impression could be mistaken). You really need something that's going to elevate her heart rate significantly for several hours every week, I think. E.g. one class a week in something, however energetic, isn't going to cut it unless she's also practising significantly in between.
My DS, similarly, is fairly uncoordinated and prefers reading to sports. For him, the things he enjoys are fencing and archery, and what keeps him fit is (a) cycling to school (6 miles per day, Mon-Fri) and (b) going to a school that has at least an hour of compulsory sport every day (though this of course doesn't help him comparatively, as all his peers get this and many of them choose to do extra sport as well).
