CMB makes an excelent point about the site visit. However, it's more than the software/OS that must be verfied. Parking (as mentioned - try hauling a trunk full of course supplies three blocks), presentation space (What?! No chairs??), location (especially in industrial parks that love to hide building numbers and names), etc... There will almost always be one major problem that's been overlooked. A site visit may not eliminate it, but it give you a better chance to prepare.