glad to hear that you like MIR 3D - thanks for the friendly words! :-)
For the typical epic brass fanfare, the foyer of the Vienna Konzerthaus would be my first choice. You can literally choose any relation between instrument and microphone, from 1m on the same level up to about 35 meters distance two floors higher :-)
The Festspielhaus Salzburg - Böhm Saal would be a close second, especially if you choose the balcony positions at the "stone end" of the hall.
If I have misunderstood your question and you are actually looking for a huge room without too much reverb, then there is only one, but a very obvious choice: Festspielhaus Salzburg - Großes Haus (i.e. the Great Hall of the famed Salzburg festival theatre). This space is really incredible, and I dare to say that we captured it really well. 8-)
Still too much reverb? Then there's a less obvious selection that could do the trick: Hall Two of The Sage Gateshead. While being renown as a typical chamber music venue, I'm using it as an additional virtual 3D space for the mix of a quite famous 7-piece brass ensemble right now that has been close-miked, too. Everybody loves the results I'm able to achieve that way. 8-)