Using an external venue for grand opening of business?

We are organizing a grand opening event for our new business and have been receiving an amazing RSVP response from our invited guests. We have confirmation from our city mayor, ward councillors, chamber of commerce board of directors, representatives of community program coordinators, and members of the business community. We may have invited more guests and dignitaries than our facility can accommodate but do not want to reduce our publicity. So it's come down to a balancing act between keeping the attendance to a moderate level but at "our" facility, or consider hosting the grand opening event at an external venue - ie. a conference hall in a hotel or at a restaurant. The nature of our business involves mobile services that are delivered on site at various institutions and residential homes, as a result we do not need a large facility from which we run our business operations. Does anyone have any suggestions as to which side we should tilt our teeter-todder? Your experience and recommendations are much appreciated.