@samantha I view each type of script based on this analogy. Suitelets are like web pages/web apps. They are useful and good for when you need interaction with the UI. RESTlets are like your very own crafted APIs that return data based on the exposed methods you make available via the RESTlet and return data based on the parameters you send it.

I view both RESTlets and Suitelets as API tools. I rarely seriously consider a suitelet as a web page.