I've been DMing for many years now. I'm in my second major campaign and I have several small campaigns under my belt. The people that I play with are the same people I started playing with almost 10 years ago. They know my style, they know my story telling, etc. It might be me, but I'm starting to get the feeling that my in-variation is starting to get predictable and formulaic. My blacksmith/shopkeep encounters are mostly the same where the proprietor always tries to undercut the players in the same way that the shopkeep down the street/in another town/on another plane does. My town encounters are fairly typical and are dominated by the player with the highest diplomacy score. I also have a feeling that I rely to much on brute force encounters and not enough on cunning. Basically, I feel like I'm in a creative rut and I have a hard time with coming up with something unique.
I'd like some advice from seasoned DMs on how I might break out of this rut and field sessions that are interesting to the players. I asked the players for feedback but it's rarely useful.