Things that DIYers forget:

Scribe molding
Touch up kit
Quarter round
Toe kick
Toe kick returns (some lines)
Light rail molding (and enough of it to account for cuts.)
Crown molding (ditto on the counting to be enough)
Starter strip for crown molding if cabinets are full overlay.
A compound crown molding design that deals with out of level ceilings.
Butt doors instead of those with a center stile. (ALWAYS!)
Finished interiors for cabinets with glass
Actually ordering the glass (it's a separate step)
Glass shelves for display cabinets.
Extra shelves for wall and tall cabinets for more levels of storage.
Check the hinging of the cabinets, (A RH cabinet has the hinge on the right side, and opens from the left.)
Upgrade from any plastic accessories to wood one. (Like the Lazy susan or cutlery organizer.)
Fillers for all runs that begin against a wall. (And accounting for those fillers in the design!)
Hinge limiter clips for wall cabinets that open towards a wall or tall cabinet.

Finishing of exposed sided. Cabinet sides are the interior maple color unless you finish them off in some way. That is a complex one and which option you choose is based on what the cabinet line offers. Skins are the cheapest and worst way. Flush plywood sides are recommended for tall cabinets that will have base and wall cabinets butt against them or molding applied to them. Same with wall cabinets on the ends that aren't prominent in the design. They should be flush sides. I always recommend upgrading the island or peninsula backs to a wainscotting panel as well as any visually prominent exposed base or wall cabinets to an integral door panel (as opposed to an applied in the field one.)

Wow thank you that was really helpful!!!

Double check dimensions for all cabinets (height, width and depth). We almost missed that the cabinet maker had our upper corner cabinet be 24" wide. For the crown molding to work out with our differing height uppers, we needed a 27" wide cabinet. That affected the widths of several other cabinets.

Also make sure that you double check measurements for your appliances to make sure that they are reflected in the cabinet design.

Check to see if your cabinet line has the option of an extended stile instead of a filler piece. It looks a little more finished. (I have both in my kitchen.)

Excellent advice fouramblues! I always do an extended stile if a pro will be installing. Not sure if that's the case here as it sounds as though there isn't a pro involved here. Fillers and scribe molding are just easier for DIY folks, as scribing a big heavy cabinet is an acquired skill---even for pros. I have one builder grade installer that couldn't do it, that's for sure.

Thank you everyone for your input it is really helpful. My husband is installing the cabinets with one of his coworkers who is a union carpenter.