We did a lot of open evenings in Sept of year 5, both GS and comp. They all seem to have lots of interactive activities on show, and encourage the kids to join in.
I really like seeing a school on a normal school day though, so dh took ds to Marling this week to their open day. We had been to the open evening back in sept, lot sof good interactive stuff, but all he noticed was the 'old' school hall.
This week, they saw other things, in particular they saw the theatre/drama dept, which had a drum kit. That was all it took for ds to decide it was OK - has drums, I want to go there
dh said it was actually quite a dull day, most of the kids were outside doing sports, very little to see. But at the end they met the head of KS3. They got talking and he really engaged the kids, sort of gave an impromptu presentation. ds really liked him, and that (with the drums) probably swung it.