Hey Dave,
I think 100 sf of cc or tile is a good offer both for you and the new client. That's what we do as well, when a new client comes from our referral forms.
If the client that gave you the referrals also gave you phone #'s then I would call the new prospects, if they gave you the address only, you should mail first then a follow up call.
Many times the HO will call the people they referred you to and let them know you will be calling.
8)