I like the look of combining a visit to Trebic and Telc, which are close, but it seems doing both from Brno is tricky.
There's an early train from Brno; 9.20, which gets into Trebic at 10.30. It's the connection from Trebic to Telc that I'm having problems with. Trains seem to take a detour and take a while. Are buses between the two frequent? I'd be looking to leave for Telc around 1-2ish. Even getting back to Brno from Telc seems tough.
Or is Mikluov and Valtice-Lednice more of a sensible day trip? Certainly the train connections work better.