I would want a clear roof, or at least mostly clear. You could work in poly panels on the south side of the roof, like sky lights. A roof vent is probably a good idea, too.

I had a friend with a business installing retaining walls and paver stone patios. He said that most homeowners underestimated their need for a poured concrete footing underneath the wall. Anyone can stack stones, but then they slowly sink into the earth over time and fall over. After he told me that, I started to notice crooked walls in back yards all the time.

Thanks, Cole, for the tips. I'm undecided about roof glazing, thinking it might be too much sun and heat in the summer, and not in the sun's path in the winter. Maybe a skylight(s) that can be covered with a shade.
I was afraid of the need for a concrete footing. It is a lot of concrete blocks, especially if I block in the trench around the raised beds. I should probably consult an architect to draw up real plans and then save up until I can hire a real contractor to build it. But I still need to learn a lot about materials like glass, insulation, and flooring choices in order to mostly design it myself.

After reading more of the posts on this forum, I started doing more research and came upon this link, which describes a greenhouse design that would be cheaper and easier to build but hold more planting bed area. If I build this design at 7'9" by 15'6" (~120 square feet), it won't need a permit. I would build it out of cedar with stationary double-pane windows. The steeply pitched roof (55 degrees) is supposed to let the most light in, while reflecting light off of the north ceiling, which is painted white. I've given up on trying to store heat in water barrels, in favor of solar panels to power vents, fans, lights, and heaters. I hope this greenhouse won't need a concrete footing.

Here is a link that might be useful: The Solar Greenhouse

About the footing, I wouldn't be intimidated by it. It's just a trench with a little gravel in the bottom and concrete poured on top. Renting a small tractor and calling a concrete truck to pour the concrete will save a lot of work.

Now that I think about it, your structure will have to attach to the ground with posts. You can still stack the stones around the base, but there's nothing to attach the wall to. So you would put the post anchors in your footing trench.

After reading further into the archives here, I found a mention of a kit that I think would meet my needs: Cedar-Built Greenhouses. I think I'd be able to get a permit for an 8' by 16', as it's 128 square feet, just 8' over what doesn't need a permit. I'm in love with these greenhouses. They offer so many options and customizations. They give you advice and drawings for foundation options. I have no carpentry experience, so it would be prudent of me to use a kit instead of trying to reinvent carpentry. It sure was fun "designing" two different styles of greenhouse, though.

Here is a link that might be useful: Cedar-Built Greenhouses