Tallest Bonfire in history was 109 feet. After that, height restrictions put in place limited Bonfire to 55 feet, but after the collapse it came out that the limit had been regularly exceeded for at least a decade. The 1999 stack would've been 70-75 feet tall when completed.
The 1992 Bonfire commission recommended limiting height to 45 feet. The Comal A&M Club bonfire was 12-15 feet tall. Just from the pics I've seen online, this year's Student Bonfire was, I'm estimating, 30-35 feet tall. Height isn't so much the important thing, methinks, as the tiered wedding cake structure. That's what give it the appearance of mass.
Sabreman '92