Hi, Jodi, welcome!
A good place to start is with Hydroguy's excellent Tips Compilation, a sticky thread at the top of this forum:
http://www.disboards.com/showthread.php?t=1520483 Lots of great info there on how to do the parks with a minimum of fuss and a maximum of fun!
October is getting to be a very busy time of year at DL, for several reasons: the Mickey's Trick or Treat parties on the weekends in California Adventure, the amazing Halloween decorations, and the fact that there are many school districts in CA,
UT and AZ that take "fall breaks" and there is a mass exodus to Anaheim to celebrate! We were there from Sun-Thurs last October on Columbus Day weekend. We just happened to hit it right, AZ had fall breaks the week before, UT was out on the day we left, and we had moderate crowds during the week. This year, I'm not so sure about; you may want to research or ask on here about Fall breaks; there's lots of AZ and UT people on here. Gay Days is the first weekend in October, and it's busy, but then weekends are always busy, anyway.
I'd suggest making the bulk of your trip during the weekdays, with one or two weekend nights in there to see Fireworks and Fantasmic, and go to the Mickey Trick or Treat party, if you'd like. See on Hydroguy's tips thread about "High season/low season tradeoff rule"... you get fireworks and F! but lots of crowds; or you get low crowds but not a lot of entertainment stuff scheduled.
Hope you have a great time regardless, and enjoy planning!
