Pineapple by itself isn't very good, but when you add 2 - 3% to a mix it works out pretty well. Like you I got a 4 oz bottle of pineapple, and it will probably last a long time.
I also use a little Pineapple in a mix I call Fuzzy Navel.
10% Blood Orange
8% Peach
2% Pineapple
Although there is more orange than peach, I can taste the peach more.