First, if you are not sure whether you want to take a tour of the Everglades, stop wondering and do it. It is without a doubt the most beautiful part of Florida.
I wanted to book a trip with my friend who grew up in Miami and had fallen in love with the Everglades as a child but had not been back in decades. We had both been on an airboat tour in central Florida previously, but I wanted something less crowded. We were booked with Capt. Greg & Son by another airboat operator and we could not have been happier. We went out for two hours with Capt. Dave (Greg's son) who has grown up in the business. My friend told me after our tour that everything Dave told us about the history, ecology, and preservation efforts to date was accurate. (And Dave even told him a few things he didn't know). It was very clear that Dave loves the history of the area, has spent a lot of time exploring it on his own, and wants to protect the Everglades. There's more than just gators to the Everglades and Capt. Dave showed us a lot of it, but rest assured you'll see the gators, too.
If you are looking for a tour for only a couple of people you will probably find this quite pricy, but the cost is not unreasonable considering the expense involved and the time Greg and Dave have to spend before and after the tour for travel and preparation. It sounds like they are amenable to having a larger group, and that would bring the cost per person down considerably. But even for only a couple people you should consider it money well spent. The Everglades is without a doubt the most beautiful part of Florida and having a private tour was well worth it to us.
Follow their advice about sunscreen, hats, and how to dress and you'll have a great time. Finally, you would probably like having an actual camera, rather than a phone camera, for this trip, but we did okay with our phones.