Seattle is in USDA 8 (average annual lows 10F-20F). Same as with deer, if you fence them out then you don't have to be subject to their whims. Otherwise, the animal controls the situation. Filter the rabbits out instead of letting them filter what you can plant and enjoy.

Rabbit-proof? Nothing is totally rabbit proof depending on its stage of growth and how hungry the bunnies are:-) Much like deer, if the rabbit populations are high enough, access is easy and the plants young and succulent, they could eat anything. Secure fencing or very alert dogs is your best defense but plants that are highly toxic or caustic (eg. hellebores, euphorbias), very spiny (eg. barberries, some hollies) or with high concentrations of pungent essential oils (lavender, rosemary) are going to be much lower on their preferred menu compared to most annuals, veggies or tender new growth perennials and shrubs.

If you do a Google search under "rabbit resistant plants" you'll turn up various listings. However a comparison of those listings will invariably offer contradictory info, affirming the bunnies' ability to munch on pretty much anything if it so moves them.

Here's one to get you started.

Here is a link that might be useful: BHG - rabbit-resistant plants

Great website link. Rabbits like to eat infant barberries.
Some people use quiet pellet guns as a solution. Short chicken wire works and there is nothing better than a smart dog.

Come on, folks! I can't believe your region has no lists of rabbit-deterring plants. I am not from the NW so I am not familiar with your plants. The gsrden under attack is on a high bluff overlooking the valley, and in zone 7.

Grow some stuff the rabbits like to eat so they will bother your plants less. Spray with pepper spray. Interplant closely with poisonous plants.

My lungwort, Pulmonaria, collection is in glorious bloom now. Nothing bothers them, they self-sow and create their own new hybrids, and when not in bloom they have gorgeous silvered foliage.