I want to thank everyone who responded to my questions about which cat to buy. At the suggestion of members of this forum, I bought a Hobie Getaway which is perfect for us. It's durable, no boom (BIG plus with child on board), fast enough for us, and front trampoline is great for my son!
You were right that a NACRA 5.0 or similar would be way too much boat! We finally got our boat out under sail Sunday and loved it. Over the last month, we had some problems raising the mast, getting out of a channel, and waiting for wind.

I put a 2hp Honda on the boat to help getting in and out. We like that a lot.

Thanks again!