I am trying something similar on the next order, while I really like the base flavors I think the mixes could be excellent!
I am planning on trying some things mixed with a few base flavors... cherry, orange, pineapple.
With the ones I've tried.... Banana, Mango (my favorite straight fruit flavor), Lemon, Apple would be good options for mixing. All of these are not as strong as some of the others and would go well as a secondary flavor.
I also really like my fruit flavors, and if I remember correctly I believe you also use the T-System. I wonder if that has anything to do with it? My dessert flavors seem to be better out of cartomizers some times while the fruits are always great out of the T-system.