Not too much I can add to the above posters.
Earl of Sandwich is delicious and a great deal. If you have the time and the funds, treat yourself to some ice cream at Ghirardelli (cone, sundae, banana split, etc) to make it really special.
If you're not shy or self concious, try dressing up for the party. There's something freeing about being someone/something else for a night.
I recommend making your own costume for a few reasons.
You can dress it up or subdued as you like; it's way less expensive than purchasing a costume; Oct/Nov is still HOT, you want to be comfortable. Most purchased costumes are nylon, itchy, hot, non-breathable. You'll be miserable quickly. I've had friends pass out/get sick from overheating.
In 2010 I made my late DH's costume and mine. White t-shirts, shorts, capris for me, all 100% cotton. I made a paint stamp from carving some inexpensive stamps from real life Dalmatian spots enlarged on a photocopier. Black waterproof (really important) inexpensive fabric paint covered all clothing. Dalmatian fabric remnants, batting for stuffing our tails, with the right bend (yes, I'm OCD), 4 floppy ears glued to headbands (6 for $1), 2 elastic headbands for collars. I attached the tails with velcro for bathroom breaks, sitting down, and some rides. Spotted sneakers for me with good insoles, gotta protect those feet! The biggest splurge was 2 dog tags made at Petsmart for Pongo and Perdita (101 Dalmatians). Even tossed in a few hidden Mickeys and the photopass photographers loved them!!
Hope to go this year, have all the materials to become Marie. White fluffy tail, headband ears, fingerless lace gloves, since Marie is a lady. Whiskers and pink facepaint for my nose. Clearance white t-shirts and capris with fluffy white fur from an old baby coat to make my fur.
Can't forget the cattitude!!!!
Comfy, cooler, cheaper and helps me get in the spirit!
Definitely get to the gates by 3:30 to get in by 4 pm as it can take some time attaching all those wrist bands.
Go with an open mind, rest as much as possible during the day. I do, and I'm always one of the last to leave. I get my money's worth out of that ticket!
I've posted on some other threads about both parties. Feel free to post and/pm with any questions.