I purchase the Frequent Fear pass with Express access and go at least six times every year. The new Rush of Fear pass is a good deal so if you don't care about going at the end of the month, go with that. I like going throughout the month so that won't work for me.
But...if you want to go as much as possible you might as well get the FFP with Express since it's the same cost as the ROF pass with express. You get more nights for your money.
My friends and I generally get Frequent Fear Plus (includes every night but Saturdays--except 9/24). Less than half the price than with express, and with 20 nights, you'll see the houses as much as you want, especially if you can get there before 5:00 at least one night a week.