Oh hostas... how I hate them, and yet love them at the same time. They're the domesticated form of plantain lily, come in hundreds of varieties, ranging from teeny tiny to GIANT. At 12" - 36", you're looking at medium varieties. I'd stick to the most common, as the rabbits probably really would eat them. They have pretty flowers, and at the upper edge of your height requirement is a standard green leaf with a white fragrant flower - very lovely scent. They are also attractive to hummingbirds. Unless you get a majority of shade in the area, stay away from the blues, as it's a waxy coating on the leaf that gives them the blue colour, which would melt away in the sun, leaving you with standard green hostas. You can get a lovely pair of variegated hostas, I can't think of the name, but there's one that's white on the outside, and one that's white on the inside. Striking when planted together. If you want to completely cover the area, you can get an umbrella shaped hosta, and then underplant with smaller varieties. I personally like the ones who make nice mounds - the tiara series would be nice, variegated in tones of green. Francis Williams is a little taller, and nice as well. Be sure to do your research before planting, though, as they are apt to be much smaller in the pots than in the ground, and tags will usually tell you the height and mound size. Most of the most common ones are fast spreaders as well(hence why they're most common, lol).
I work for my mother's plant business, and her specialty is actually hostas. She's got about 100 varieties at the moment, and always adding more. They're very hardy plants, lovely foliage, most do well in the sun(except the blue varieties). We have some that have literally been in pots for 2 or 3 years, and they keep coming back. Have had no issues with the heat this year, the hostas are the only thing that haven't really needed much water without wilting. As I said, though, go with the most common, as they are definitely the hardiest, and will stand up to being occasionally munched much better than some of the fancier varieties.
I'd offer to sell you some of my mum's, but it's quite a drive from there to here, even if for super cheap hostas.