Every time I create a new site collection I regularly forget to enable the use of different site templates below the top-level site. Invariably that means I’m limited to using the Publishing Site with Workflow template—fine for most of what I do despite the “with Workflow” bit adding extra hassle but I usually end up thinking you can’t create sites using other templates a child sites below a Publishing Portal.
Well that’s just silly—the extra site templates simply need to be made available through Site Settings –> Page layouts and site templates. Select the individual templates you want to make accessible or select Subsites can use any site template and you’re off. No features to activate in one of four different locations, no config to change, easy unless your memory is like sieve.
Ps. Zabi has posted a nice visual walkthrough showing you exactly how to make this change.