When trying out these tutorials (T4 Tutorial: Creating reusable code generation templates) I noticed that although I was using plain c# I didn't get any intellisense, probably because of the file extension (.tt)
Isn't there anyway to say to Visual Studio to consider those .tt files as .cs files and thus get the correct intellisense help?
You can purchase the professional version of T4 Editor. It works very well in standalone .tt files, but unfortunately, due to the differences in how the pro version of T4 Editor and T4 itself compile the templates, you will get false errors reported for this tutorial, which relies on T4 Toolbox.