Classical music was originally played on festive occasions: as liturgy in churches, at royal banquets, at garden parties, on barges along the river, and so forth.
It began to change around the time of Beethoven, when orchestras got larger and larger and then huge, and when it moved from ducal banquet chambers to public concert halls.
One of the few great developments in the classical music scene over the past thirty or forty years has been the return to ancient instruments and the return to chamber orchestras, instead of everying being done on the scale of the Boston or Philadelophia symphony orchestras.
I had a seat at the Friday afternoon concerts of the Boston Symphony for about eight years, and it was a real pleasure, but one I would not want to return to.
That's why Tanglewood is so pleasant, or the operas at Glyndebourne, because venues like these are more like the way music ought to be heard--at a festive occasion, during dinner, at Mass (although regretably the liturgists who presently control the music are idiots, so the real experience is now very rare), where the music honors God, or the King, or a family or village festivity.
I'd also recommend summer opera at Glimmerglass, in Cooperstown, NY. A beautiful setting to enjoy a fine production.