LOVE the idea!!
Just some things to think about.
You will need top notch scheduling, because some people will want to be their with their dogs and some won't. So it will be a challenge in the scheduling department to fill all the spots in both areas when they want to come together PLUS the separate spots for those that don't want to come together (all to stay in business!).
Will you cater to only people with pets? That would help determine your layout. If it's only people with pets, it will be easier if you want the areas near each other. But if you're also catering to people without pets, they may not be interested in sitting near pet areas.
Also, just some of the things that I love about my groomer.... they are holistic groomers, so like you want to, they offer top notch food and treats. But they also have tons of the newest information and newest research (Do your dogs need to be vaccinated every year?, What natural products help with ear infections?, etc.) That always makes me feel like I'm in the right place.
Good Luck!