Williams-Sonoma. You'll be looking at some of the things wondering what they are. Ask for help.
Don't confuse our love for tools with her love for kitchen tools. Unless you know better. I would not buy my wife anything for the kitchen as a B-day/mother's day/anniversary gift. She prefers a massage, a babysitter for a night out, even bath and body works soaps/scrubs or new unmentionables from that pink store at the mall. There are benefits to shopping there for me too.
If you do know that she wants new kitchen things, then I highly recommend a nice set of cutlery or even taking her current cutlery and getting it sharpened. It can make a HUGE difference. I sold Cutco brand cutlery as a side job when I was in college. I'm a terrible salesman, but I still have those knives (20 years old) and I still use them daily. I've added onto my demo set with a few pieces purchased online. I used to hate visiting my sister's house because she had terrible knives. Another idea - a digital thermometer. It beats cutting everything open while it's cooking to see if it's done. You end up with much more flavorful, juicier meat that you can serve, confident that it's cooked enough to be safe (especially with chicken).
You might also think about cooking lessons - again, you have to know your wife and think about how this would go over. Would she get snippy? (What are you trying to say?). My wife took a series of cooking classes at a local college and picked up some great tips.
New pans are great, but unless you have deep pockets, think carefully about the most used pans and what is in need of upgrading. I recently spent close to $300 for 3 pans. I use of them daily (omelet for breakfast), another one 2-3 times per week, and the last, well, not so much, but it was only $30 more when I bought that daily-use pan.