So are you looking to spec the house and have it built? Or moving into a house that was spec-built?
When we bought our house, (fairly spec-homed) we learned after that the builder could have done much more to accomodate changes. It was just the lazy realtor/construction sales rep (son of the owner kind of deal) that was too lazy to offer us the various options.
It wouldn't hurt to identify the actual foreman at the community and "Bump into him" while out looking at plots. Then ask him about what is available in addition to just the sales guy.
Also, inquire about the low voltage wiring. When we built ours, the crew didn't care if we came in after the electrical was roughed in, but before the insulation was installed and add some more low voltage stuff.
I was able to go in on a Saturday afternoon and easily add a number of runs of CAT 5e and coax that would have cost me over $500 to have them do it.
(Not really related to HT, but I also replaced the light junction boxes in each of the bedrooms with ones that were designed to support ceiling fans prior to insulation and drywall. The builder wanted an arm and leg to install ceiling fans so we just speced the most basic light fixtures then installed the ceiling fans ourselves after moving in.)