This is an old pattern but I can not recommend Moss Stitch enough for cushion covers. Its a firm and none stretch stitch that will give you a cushion cover that lasts years with out stretching out of shape.
Very decorative and can look so different, with just the colour combination you can achieve stripes spots or a tweed look.
Moss stitch blanket in a tweed finish, the same combination as the cushion, again its the same stitch just a different colour combination
Colour combinations give different looks but the stitch does change
Same Moss Stitch different colour combo using space dyed yarn and a plain yarn gives something similar to a Fair Isle look
same Moss stitch below gives a striped look
same stitch just different combination of colour combination gives you a spot
is a link to several projects using
MOSS STITCH and showing you all the variations.