I don't have any personal experience designing a shelter but I have a few random thoughts over the years. When you say 'soft and furries' do you mean puppies and kittens? If so, having a nice space with natural light and access to an outdoor play yard would be great for people who want to play with the babies. You might want a place for people to take off their shoes and wash their hands.
I've always thought cat cafes were a great idea. You have to keep the animals separate from the food area (health codes) but if you had a place where a little coffee and sandwich cart could be set up just outside of your meet and greet area, people could come hang out with and socialize the animals while they eat lunch or have a coffee.
If you built a modest 2 bedroom apartment over the facility, you could offer recent vet graduates or dog trainers free lodging in exchange for their services and have a person on call for after hour emergencies. I've never done the math but this investment might pay for itself in a few years. If the apartment was set up for fostering, they could look after tough cases at home.
Lots of fresh air, natural light and ways to dampen the noise will go a long way to making it pleasant for everyone. Perhaps a speaker system so you can play relaxing music and nature sounds, both of which have shown to reduce stress.
If you make this new space enjoyable to be in and make it easy and fun to interact with the animals, I bet people will come visit just because the like being there.
That's a big task you've got. Good luck! Let us know how it turns out : )
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