How do you use actually your bitcoins...And which sites accept bitcoins?
Where can we exchange bitcoins except local traders?
Here's a list that should be somewhat up-to-date. Note that Bitcoin acceptance may differ based on your region (eg. Expedia only accepts BTC payments on their US website).
https://99bitcoins.com/who-accepts-bitcoins-payment-companies-stores-take-bitcoins/Noteable other (non-US) merchants include: aohostels.com (hotel / hostel rooms) and lieferando.de / lieferservice.at (food delivery service)
I personally mostly use BTC for namecheap, Steam and HumbleBundle (in cases where HumbleBundle accepts BTC, which is unfortunately not always).
Noteable exchange platforms for buying / selling BTC include: Coinbase.com, Kraken.com, Bitstamp.net and Bitcoin.de. There are a couple other ones that have a heavy focus on alts, but most of them don't allow for direct bank transfers.