We've done two wonderful Escalante trips that you might want to consider, although we were there in the spring and I don't know what conditions are like in September:
1) Boulder Mail Trail to Escalante River - Many people go from the BMT down Death Hollow to the Escalante, and you might be able to turn that into a 4-night trip, especially if you camp an extra night where Death Hollow meets the Escalante and do an out-and-back to the west to explore along the river. (There's a wonderful huge alcove that we really loved about 4 miles west of the confluence.) We did a different route, though; instead, we went on the BMT all the way to its southwestern end, picked up the river there, and hiked east along the river to the Hwy 12 bridge. We loved our route and found the mix of scenery along the BMT and river to be excellent. You would need a shuttle to the trailhead (Boulder airstrip) or be willing to hitch a ride; we used a shuttle. We finished at the Hwy 12 bridge, but if you want to extend the trip I'm pretty sure you could continue along the river east of Hwy 12 and explore Phipps Arch as an out-and-back. If you consider doing this the way we did, I don't know what water availability on the western half of BMT would be like in September. There's definitely water in Death Hollow but maybe not in Mamie Creek, so that could be an issue. If there is water at Mamie, you could camp nearby and enjoy the out-and-back to beautiful Mamie Natural Bridge.
2) Little Death Hollow & Wolverine with a couple of nights base camping near the Escalante River - We loved this trip, too! LDH and Wolverine are really fun and interesting, plus we spent two wonderful days in the middle exploring the fascinating scenery on the south/west side of the river. There are a couple of specific spots where you can exit the river to get to the wonders on the other side. As an adventurous bunch, you'd probably do fine with this. No ropes are needed but there are some spicy moments and great places to check out. If you're interested, let me know and I'll be happy to provide more info.