While you are developing Server Controls, keep in mind that their PRIMARY USE is REuse. Any time you spend now making it easy to use will reap you many times that amount while using the control in the development environment. As a simple solution, make sure you provide an accurate representation for the IDE of what you control will look like when it is loaded. Whether you do this with the Render method or with designer classes, make it as simple and accurate as possible. Of course, all bets are off if you are not building visual controls but the primary rule is keep it simple, stupid.