The villa is now re-open after extensive renovations and it is necessary to book ahead for tours, which cost about $20.00 (I booked on-line about three weeks before my April 14, 2012 tour.)
The only tours in English are the so-called "technical" tours which last about 90 minutes (the other tour is about an hour). The technical tour includes the (state of the art at the time) air-conditioning and heating facilities, whose mechanisms were explained by the guide in an easy to understand manner. My tour group had about ten people in it so it did not feel crowded.
The villa is in a quiet residential area of Brno, easily accessible in about ten minutes by several tram and bus lines, or about a 40 minute walk from the train station through the old town (very nice) then for about 15 minutes on a run down stretch of a wide, much trafficked ugly avenue and then about five minutes more along a tree-lined street.
Even those who are familiar with, or fans of Mies Van de Rohe will find a visit fascinating. My guide was excellent and well informed. Besides explaining the minimalist philosophy of Van de Rohe, and how he made it a reality in this residence, the guide also provided a history (very sad for the most part) of the house in the period following the Tugendhat's flight from Nazi-occupied Czechoslovakia and abandonment of the villa up until the present. It is a microcosm of what happened to the people of the Czech Republic and their country, so those with a interest in the history will also find the tour interesting.
Although the upstairs bedrooms looked to me like motel rooms from the 50s, I imagine this is a tribute to the influence of Van de Rohe on modern architecture. It's when the group went downstairs to the living area, library and dining room that there were audible gasps. A huge onyx wall, rosewood and ebony doors, walls, tables and shelving, 8 or 9 foot high windows that looked out over the sloping grounds and a magnificent view of the Brno skyline and of course, those Barcelona chairs are all amazing and even to this non-architect's eye, form a textbook definition of what "less is more" can mean.
Unfortunately, most of the kitchen and laundry facilities were taken out but the guide said they are looking for period pieces to display.
The city of Brno is interesting in its own right, with a lovely old section and some quite streets just right for wandering. There is also an extensive art scene, with several galleries scattered around.