I have 3 at home, plus one at work. Main audio; HT; and a small combination Audio/2 channel HT in the home office (bedroom). HT is for the family; Main Audio system for me; and the den/home office system for when working, when the HT is in use, or when my wife wants to do some work and listen to her music. The Main Audio system and HT system are on the same floor with no sound buffer, so they cannot be used at the same time.
Different sound need and goals. The home office combo audio/2ch HT system has an integrated amp, turntable, tuner, tape deck, VCR, and has a Stan Warren modified DVD player, so it works well with music and for movies when going to the Sony TV.
The HT system is modest but does the job; Onkyo HT receiver, B&W 302s all around with CC3 center and a REL Q100E sub; plus DVD player, VCR and a Laserdisc player.
The Audio system is too complex to list in detail. It is by far the best of the bunch.
I believe the Champ is Jeff in Montreal with 5 systems at last count. (I suggest he needed one in his bathroom too #6).