I am not familiar with your area so my comments should be filtered accordingly.
The Flying Scot is a great boat. $11k sounds high for the boat you are describing. You should be able to pick up one in good shape for aroudn $5k. It obviously depends on the year. Check out the boats listed at fssa.com (http://www.fssa.com/ht/shop/shop-caveat-emptor.htm)
. Also, check Craigslist, eBay, SailingTexas. I picked mine up from someone who was not using it and had not listed it officially for sale yet. I sail with my wife (new to sailing) and boys 3 & 5 y.o.
My dad has a Harpoon. Another great boat. Very similar in many ways to the Scot. A little slower. Unsinkable and more room to move around in even though it is a smaller boat. My dad sails on small lakes and Lake Michigan.
Both of these boats are good for the lakes and semi-protected waters. I would not want to be caught out on the big lake in a blow, especially with the kids. Remember, these are both centerboard boats with out a heavy keel. Easy to trailer, but corresponding risk of capsizing. I have never felt at risk sailing with the kids when I am conservative - racing I start feeling nervous a couple of times with the gunnel in the water, but the boat was still incredibly stable.
Yes, the Lightning and the Thistle are in a similar size range. Lightning has lots of lines to tweak everything. If I remember, neither of them has bench seats, instead you would be sitting on the rail - not great for a small kid.
Since it sounds like you are in more open water, you might want to consider something like a Catalina 22. Head, cabin, keel. It is a different animal entirely from the dinghies. I enjoy being closer to the water with a simpler boat therefore the Flying Scot instead of a Catalina.
By the way, forget rolling any of these boats to the water by hand. You would need a large crew of strong men. If you want to do that you would need something like a Catalina 14.2 or a Flying Junior (even then it might be a stretch for you and your wife).
If you want more details of either the Scot or the Harpoon feel free to PM me.