Destination Flag: Not so much an upgrade as a necessary part of making a tour office. This sets where the tour group ends up once the tour is over and where they'll spend some time admiring the view. Make sure it's set in a beautiful area.
Mimeographed Handout: The tour office gives visitors information on a single paper with black and white printing from a mimeograph. This is a cheap way to mass produce handouts.
Four-Color Brochure: The tour office gives visitors information on a full brochure with colored illustrations. This increases the upkeep to $20 a month, but improves the tour office's service quality by 20%.