Dont forget you can also do like a strip along the wall (1X5, 1X6 and so on and so on) the only thing is they cant run actual laps, but they can run back and forth. 2X? are great to, like a 2X4, 2X5, etc etc, they actually do save space and its really worth it in the end (helps with smell AND looks. But most importantly the piggies will LOVE it) You just have to make and create with your own ideas, you can also do an "L" shaped cage too if say you have to bend it around the corner of a wall or a couch or something. Just get creative, thats one of the best parts of these cages I think! Anyways, good luck either way you go!
OH! also dont forget to check around the galleries for ideas too!