Among the top conference centres in Scotland are Peebles Hydro; Gleneagles Hotel and Prestonfield House.
Peebles Hydro is only 30 miles from here but not on a railway route.
Gleneagles has a railway station where the hotel minibus will collect you (an hour by train from Glasgow or Edinburgh)
Prestonfield House is on the outskirts of Edinburgh and has the bonus that the staff wear black kilts.