I applied to five. So far interviewed by 2 and accepted by both. I declined an interview at a 3rd school. Debating whether or not to go to an interview at school 4 in mid-January.
Study the out of state schools carefully. In some states it is nearly impossible to establish residency, even if you move their and buy a house and pay property and income tax. You can be considered a legal resident of the state but the school will still consider you a nonresident for the purposes of determining which fees you pay. Had I known this, I would have knocked 2 of the schools off of my list.
Also, schools want hefty deposits right away after they conditionally accept you.