I really love Brambleberrys lemon cake. It's so delicious smelling and very strong and it sticks well in CP. I also just bought a sample of lemon squares from Natures garden and it smells almost exactly the same, but I haven't tested it in soap yet.
I tried the Lemon Squares years ago when I first started soaping and I remember liking it, but I can't remember how long it stuck around for. I don't like bakery scents so I did not really give it much thought. Sorry, I was not much help.