The Marbach castle was a very nice place for a conference. You live where the conference is and that gives you time to socialize with the other attendees. Especially fun was it to try the onsite driving range. There is also bowling and a swimming pool in the castle. The food was great and the conference rooms had good chairs and electric outlets everywhere. Best of it all was the relaxed atmosphere and the incredible view when you had breakfast on the balcony.
The WIFI was stable and run at 7 Mbit/second. In the room you got a bathrobe and a pair of slippers. I got a room with a patio door with my own garden. The only bad thing about this place is that there is a road dividing the property into two parts. The main building on the one side and the living quarters on the other. There was not that much traffic, but when the cars came they drove quite fast and the visibility was not great. If this is your first time and you want to see some sites the taxi driver suggested a nearby village called Stein am Rein. Looks nice when we passed that by.