Our main jumping ring is 220 x 110 and it is VERY easy to get in a typical hunter course of 2 outside lines (i think the biggest we've done is about 6 strides in the line, on 12 foot stride), 2 diagonal lines, a single, and various singles for the tighter jumper/eq turns. We've also easily added some triple combinations and some pretty complex gymnastics in there as well.
As far as scale goes... when you set a course, the average horse stride is supposed to be 12 feet. You allow for 6 feet in front of the jump for take off and 6 feet after for landing. So when you set a 5 stride line there will be 72 feet inbetween the 2 jumps. So if you have an outside line set on the 200ft length of the arena, you'd have about 4 or 5 strides from the corner to the first jump, 5 strides, and about 4 or 5 strides until you hit then next corner. Does that make sense?