Thanks for the advice! I think I will start with a 6" or maybe an 8". I don't want the focal length to be too high, though, because I'm terrible with the low FOV's. Is it possible to get an eyepiece that produces a low power despite a high focal length? I heard that if I wanted a spherical mirror for a scope this size, the focal length would be over 2000mm, so I'd need an eyepiece that's 50mm or more. Do these exist?

I also have a couple slightly random questions:

1) Does any magnification happen at all without the eyepiece? What if I just looked directly at the secondary mirror? How does focal length relate to what I'd see in that case?

2) Do you think it'd be possible to increase aperture without increasing magnification? I always wondered what the sky would look like through a pair of 1x50 binoculars. It'd be extra awesome if they were thin enough to wear like glasses, and the resulting image wasn't vignetted. Also, if I could wear them while riding around the skies on my unicorn.