Is the BBQ an add-on that can easily be done after the fact, or is it intergral with the cement and landscape work and just won't be the same if you add it later? If so, I'd get the BBQ BUT spend the little bit extra to have everything set up to install a SWG. ie. electrical, timer, and piping with caps.

If the BBQ is an easy add-on, I'd get the SWG from the start too.