It would be great to be able to chose which tab opens first/defaults when you click on a channel. At the moment you see the Posts tab first and have to click again to get to Files. Ive found that most people are predominantly after files (use notifications and @mentions to alert them to important comms) and so would prefer it see the Files tab as soon as they click on the channel they want. this ability would then allow people to customize to suit users and workflow.