Be sure to use fresh rosemary for this dish; dried rosemary won't give you the woody flavor that you need.
Long thin pasta noodles are perfect here, so go for spaghetti, linguine, angel hair, or fusilli lunghi.
Go for 20-25, which gives a serving of 10-12 smallish shrimp per person and makes sure they cook in the given time frame. If using frozen shrimp, ensure they are fully defrosted.