I think a box of 64 crayons would be a good description for a cottage garden. Sounds just right to me.
Personally, I like a mix of shrubs and perennials. I don't do many annuals, but I like them in the gardens. This year I seem to have foxgloves going crazy. I try to get the foxgloves so they are equal each year, but no matter how I seed every year it seems heavier ever other year.
One plant I found I really like is persicaria polymorpha. Those are really standouts.
