really big front windows on the top deck
I can also vouch for the superiority of East Lancs (later Optare) top deck windows, having grown up looking out of them! Having said that, I'm referring to Omnidekkas rather than Olympiiiiiiiii (idk I just really wanted to do that), but the upper deck front and side windows on their ADL replacements in my area aren't nearly as good.
(Especially when NCT put advertising banners across the upper deck windscreens of every bus - it blocked the view on the E400s but the Omnidekkas were fine because of how deep the windscreens are - luckily they stopped doing that by the time they introduced the E400 Cities as their upper deck front windows are even shallower!)