Hi Andy, welcome to the DIS.
There are a lot of threads that you'll find useful. The trip reports are probably a good place to get some ideas of what you'd like to do. The older one I would imagine will like IOA and the thrill rides there. It's also worth thinking about Busch Gardens as they have some excellent coasters and animal exibits.
With the ages of your kids they should be ok to go straight through the day in the park without a rest, but still try to have a little "down time" at the hottest part of the day, Lunch somewhere either inside or at least in the shade and plan some indoor rides for the hour or so immediately after lunch.
Even in October it's still pretty warm, you may find any ladies in the group will like to have a cardigan for the restaurants in the evenings as they can get quite cold with the air conditioning.
If you haven't already done so, I'd suggest buying Simon Veness's excellent "Brit's guide to Orlando " guide book. Simon is a regular on this site, but his book is still a valuable source of information, it is significantly better than other guidebooks on the things outside of Disney, which make up a large portion of things your going to want to do.
DO try to have a roiugh itinerary, it sounds very "anoraky" thing to do, but it really does help to have a plan of which parks on which days. I never stick to my plan and swap the days around, but it does help to keep track of what you need to fit in during the remaining days and means you don't cram too much in early ( or late) in the holiday .
Hope to hear some more from you as you get your plans together.
We are going on our first ever trip to Florida on October 28th to November 18th. We are staying at Mango Key villa resort about 5 miles away from DW. Can anybody give us advice about how to manage our time in the parks so our boys get the most out of our trip (we have a 6 year old and a 13 year old) who are really excited about our holiday.
