Let players look at Graveyards/Banished Zones/Extra Decks for as long as they want. It gets VERY frustrating when you're trying to analyze either player's Graveyards in order to gauge the game state and what your potential moves are when suddenly, it closes because you're going into a different phase or your opp is doing something...
Also, you should at least let players hold priority to read the cards that have been revealed. Sometimes, I barely get a glance at what someone added to their hand with pot/sangan/etc...