If you use curry, check their curry powders. I especially love the
hot and the Maharajah curry powders. Like Cyn, I really like the Aleppo pepper as well as their regular pepper flakes, the chipotle powder and dried whole chipotles, and all the paprikas. The shallot salt was nice, but it became rock hard very quickly and I had to toss it. For the few times I need onion or garlic powder, I think Penzeys granulated products are great.
Just personal preference, but we're not so crazy about a lot of their blends, we like the McCormick steak blends (the Montreal Steak Blend is awesome) better than Penzeys' and just this week dh tossed several jars of blends we've purchased and never used, but I see he saved the Northwoods Fire and Bicentennial Rub.
Buttermilk and green goddess salad dressing mixes aren't bad in a pinch and I really love the jar of beef soup base I got from them. They have several different flavors, I've only used beef, generally when a recipe calls for canned beef broth.
Oh, and I use the corned beef spice mix for corning brisket. Their cinnamon is wonderful. I love Penzeys, have way too many of their products.