Shelves;)

I really like my vertical storage in one cabinet for cookie sheets, cutting boards, platters, etc. I also just put a short pull-out drawer in the cabinet under the kitchen sink that I think I'm going to really like. I really hated trying to get something out of the back of this cabinet. Oh, not sure that it qualifies as essential but I LOVE the soft close hinges and drawers. Good luck.

We put a tilt tray in where the false drawer front is in front of the sink. It's hinged and tips out to reveal a holder for sponges & scrapers.

Below our cooktop, we have a spice drawer with an insert that that tips the spice bottles up (like stadium seating for spices!) for easy acess identification.

I love my pullout pantries, I have them in my kitchen and in the laundry.

The most popular cabinet inserts are a pull out trash can, a pull out pantry and tray dividers above the fridge. And lots of drawers, with good quality full extension soft close glides lke Blum or Grass. A good quality tough KCMA certified greenguard cabinet is also important for your environment (low to no formeldehyde) and to resist wear and tear. Take a look at what KCMA certification means and what companies have to put their products through to achieve it.

http://www.kcma.org/Homeowners/Performance_Testing_and_Certification_Program