We did 2 water tours with Discover El Nido which was an amazing group. One tour was tour A and I can't recall the other one. We took their suggestion based on water conditions on which tour to take. That tour was the one that included Snake Island. Snake Island itself is more of a sand bar with a short hike up to the top of one island for the views. There was no snorkeling at this particular location. My sister who is a snorkeling fanatic was able to snorkel at about 4 out of the 7 or 8 stops we made at this particular tour. Lots of sea life to see in the snorkel spots. Especially if you are the type of snorkeler who will dive down and get up close to the coral. If not, bring a go pro camera and your tour guide, Ruben, will take amazing footage with your go pro of all the different sea life below. One of the perks of going with this tour company is that their cook is amazing. Just thinking about it makes my mouth water. lol We didn't stay long enough to fit in a visit to Nacpan Beach but that was our backup plan if the waters were too rough for the boats. We stayed at El Nido town at Lagun Hotel. It's newer and the facilities are clean, well decorated, and the staff was the epitome of hospitality. Highly recommend staying there! As for staying overnight at the islands on the tour, I don't think it is possible. They are pretty rural and no accommodations for tourists that I can recall. The rule was always leave nothing and take nothing to preserve the beaches as much as possible. Most tours end by 5 pmish and every start and end of the tour, the boats have to check in and out with the Coast Guard with passenger manifests.