I'm a big fan of Camp Bow Wow. We've used the one here several times, and haven't had any issues, so far. The longest period of time that Ian has stayed there was for two nights, but in June my hubby and I will be going to St. Lucia for a week, and plan to bring him there. Like you, I will be a nervous wreck because we have never left him anywhere for that long.
https://www.google.com/#q=chicago+camp+bow+wow