I played in a very similiar tourney last year at one of the local bars. One thing you could consider doing is having little gifts to get out each tourney, such as a $10 gift certificate to the bar for first place etc. While poker is fun most of the time, having a small prize might make players play more like something is on the line, and if they play good they will be rewarded in a short time, not months down the road. And our "final event" was at the end of every month instead of 4, but no big deal.

the starting blinds might be a little high. Although I'm not familiar with live play, but you don't get too many hands in 15 minutes and the players are already starting with only 20bb. I'm assuming the next bling increase is either 75/150 or 100/200 and if that's the case then alot of the players will already be on a somewhat short stack after only seeing maybe 20 or so hands. Just something to consider.