ID
Waiver(s)
Cash/Credit card/Giftcards
Race information (expo times, expo layout, etc)
Race Day:
Shoes (multiple pairs for multiple races)
Shirt
Shorts
Sports bra/undergarments
Socks
Throw away clothes or garbage bag (great for cold/wet weather)
Hair ties
Sparkly Soul Headbands
Handheld bottle/Hydration belt
Bib holder/Race Belt
iPod (and charger)
Garmin/watch (and charger)
RoadID
Pre-race food (banana, power bar, etc)
Fuel - Gu, chews, etc
Vaseline/Body Glide
KT Tape (make sure to precut your strips or have scissors)
Sunglasses
Hat/Visor
Sunscreen
Chapstick
Medication/Inhaler
Post Race:
Park Tickets
Recovery shoes/sandals
Recovery sleeves/socks
Foam Roller/The Stick
Travel first aid kit
Blister Pads
Gallon bags for icepacks
Plastic bag for dirty race clothes (or use gear check bag)
Biofreeze
Tylenol
General Items:
Shirts
Jacket
Shorts
Jeans
Undergarments
Socks
Comfortable shoes
Bathing Suit (if doing pool time)
Pajamas
Cell phone charger
Portable cellphone charger
Medications
Toiletries (shampoo, conditioner, body wash, razor, etc)
Yes, race-cation packing can be stressful. Just make your list and check it twice. Remember that a lot of what you might need can be purchased at your destination in a worst case scenario.