Much like Pilgrim although my preference is unleavened bread and wine, mainly because as I understand it, those are what the early Christians actually used. However, the Church I attend uses grape juice and leavened bread.
The reason why I don't insist on going to a Church that uses wine and unleavened bread is because it is one of the issues that I am not dogmatic about.

As for frequency, it is administered once a month.
To be honest, although I just thought about this, every Church I have been a member of administers the Lord's Supper once a month.

Tom