My family and I spent 4 days at Sanibel Siesta and had a wonderful experience! While I didn't interact with the staff very much, the few times I did they were very friendly and helpful. The unit we stayed in was a lot LARGER than I was expecting, basically it's a two bedroom apartment.
It's right next to the pool and a 3 minute walk to the beach. The other nice thing is that the unit came with a beach umbrella, 12 or so beach chairs, a boogie board, and some kid's beach toys. The only thing missing from the rooms are beach towels, so make sure you pack one for everyone prior to arriving. You can rent them from the main office, but the rate seemed a bit pricey to me so we didn't rent any and trying to find other beach towels on the island didn't return any better results (very pricey and of low quality).
The overall state of the room was good, but there were a few things that should have been taken care of prior to our arrival...first, the batteries in the remote on the Master Bedroom TV had leaked battery acid all inside the remote and onto the dresser (not too big of a deal because I wasn't staying at the hotel to watch TV, but still I'm not sure how it was overlooked). Secondly, prior to getting in bed on the first night after pulling back the sheets there was a large, fresh shoe print on one of the pillow cases. NO BUENO!
Overall, my family and I were very pleased with our stay at Sanibel Siesta and will definitely consider staying there again in the future.