How about the temp that allows the "hottest" person to work comfortably in short sleeves? Lower if anyone needs to move around a lot. You can always put on more clothing, but it's hard to wear less than short sleeves and thin pants in an office. I wear a sleeveless top and linen summer pants at work a lot now, even when it's seriously cold out... And then have a jacket or cardigan handy.
Winter riding is much less about badassery and much more about bundle-uppery. - malkin
1995 Kona Cinder Cone commuterFrankenbike/Selle Italia SLR Lady Gel Flow
2008 white Nakamura Summit Custom mtb/Terry Falcon X
2000 Schwinn Fastback Comp road bike/Specialized Jett