I have the bikesters for commuting on the MTB (slicked) - they are good, cheap, fab quality, no insert, but I wear shorts under.
Working in an area that is 'infested' with young female students (90% female) I think it better to be walking into the office with slightly more discrete tights (i.e. bikesters), than full blown road lycra.....I generally get comments from female staff when I turn up in the road stuff - "ohh very fit and active"...... some near 40 year old in full lycra is scary for 18-23 year olds......I'd be locked up..........