I've not ridden that board, but that is probably a decent start. You can get it new for about $300. I would say its on the fragile side for beginners, but for $150, you don't have much to lose.
This is the coex I like for beginners (bullet proof)
The skim board someone mentioned above (Phase 5) is also pretty bulletproof. But they are not an easy board for beginners, and are really slick. My wife uses a Phase 5 Daniello Pro that I love, but we've had some pretty good face plants on that one with the board sliding out from underneath us
I prefer Surfstyle for that reason. With all those fins, I can land completely off balance, and as long as I have my toes on a rail, those fins will not let the board slide.
If you are 165, you can ride all those boards with no issue. The kids will need something smaller. I think the Coex will work. I've gotten smaller kids up on it, but I don't know what a 9 and 12 year old weigh
The Coex will not support weights much above 175 very well, unless you have a reall large wave. So this board could be the 'everyone' board if you aren't carrying heavier riders.
Bottom line, you need to have a throw away board that is medium sized and not fragile for guests. They will run these boards into the back of the boat, and you won't be happy if the board is ruined as a result of it. They will also get walked on accidentally and dinged if they are fragile. You and your wife should learn on something mid ranged (maybe that LF board you mentioned), then get rid of it and buy a high end board when you've learned. The kids will likely need the smallest board they make.