Another thing to keep in mind is that depending on the matchups, you may be able to buy upper level seats for a session and "sneak" to unoccupied seats in the lower level for the second game. Much easier the fewer there are in your group or you're alone and also easier to do in the evening session as fans of the first game teams and neutrals will start to trickle out as it's getting late. Two years ago I went to both opening round sessions in Columbus as well as the Sweet 16 in Louisville. After FDU/Purdue, I snuck down and sat with FAU fans against Memphis. After Alabama/San Diego State in Louisville, I snuck down and sat with Princeton fans (great fans!) against Creighton.
For about 10 years, before kids in school, I used to buy 4 tickets to the first-round sites closest to me in Cleveland as soon as they were available. Then when teams were announced I'd usually sell 2. I nearly always had my expenses covered, more or less, and often came away with a small profit. For me, the opening rounds were the best by far.