I was going to mention the Horror Make-up Show. It is air-conditioned with comfy chairs. Or the Animal Actors show. Not air-conditioned and the benches are kind of uncomfortable, but it is a great place to stop moving for a bit.
One thing that caught my attention is that you are going in September. We regularly go towards the end of September and it is going to be HOT. Like surface of the sun HOT. It is quite likely that NONE of your party is going to be able to make it all day without a break. So plan 2 hours (or so) to go back to your hotel and freshen up (travel time 30 mins round-trip, 1 hour of down time, 30 mins to settle in and to get moving again) so you can all finish the day strong. If your husband feels that he needs more than that (maybe heading back to the hotel a bit earlier), the fact that you will be following soon may take the sting out of it. And if you are lucky, you can also time it to miss the usual mid-afternoon rain (we've gotten quite lucky/skilled at timing this).
Also, the early entry park is likely to open at 7 a.m. (in September, Studios is usually the EE park) so you will probably have about 11-12 park hours. With the Express Pass and likely low crowds (assuming that you are not going over Labor Day weekend), you should be able to fit A LOT into the day. Missing a couple of hours so that you can finish the day strong is probably a good trade-off.