Reading
New ambitious manager who has promised a fluent continental style of play (

Academy prospects getting the opportunity in the first team
BR promising "if you're good enough, you'll play" which was a very welcome change from "Coppell's favourites" at the time
Forest
Had spent a lot in the summer
Genuine prospects of promotion
First game of new season attracts fans for the "away day"
To be fair, I'm surprised the two attendances mentioned aren't much more further apart.