I did the same when I was younger. I always tried to enter the locked door in the beauty machine room, for example, or get into the Stop 'N' Swop room in Gobi's Valley. Though the ice key is probably the biggest tease of all.
Nowadays I know the entire game inside-out. I've moon jumped my way in and out of every wall, looked at and edited the level models in Blender, read every single Stop 'N' Swop theory you could imagine...
Banjo-Kazooie has pretty much consumed half my life searching for hidden secrets.
Playtonic have already said they want to include lots of secrets and Easter eggs in Ukulele, so I'm positive we'll have lots to look for! My only concern is 'data miners'/hackers. They're bound to rip the game a part in a matter of weeks and spoil all the surprises.