I was able to put a bunch of stuff together for both kids (dd-6 & ds-2) before we left...and packed it all in their backpacks.
Did it all at local toy stores, The
Disney Store and our local Dollar Store!
TDS has EXCELLENT sales. I stocked up on the character sets (currently on sale for $5 each), the smaller stuffed animals (3/$10..got the whole Fab 5 and then some, Mousekeeping has a ball w/ them!), family sets of t-shirts ($5/ea), spinny light toys, and other smaller items in the deep discount section.
The Dollar Store is great for stickers, pencils, crayons, coloring/activity books, flash cards and GLOW stuff (necklaces, bracelets, lanyards and balls).
Our local toy store was great for magnet sets (TDS now has some for Playhouse Disney), activity books, travel magnadoodle and other small stuff.
Everything was Disney themed except the magnadoodle (that was a Diego one).
I wouldn't bother w/ a tote bag... just another thing to bring home! Each of our kids had their own backpack and they weren't allowed to look in them until we were ON the plane! I held back the stuffed characters and brought them out throughout the week.
Have fun! Dh griped a bit about my "pre trip" purchases...but when he saw how happy the kids were...and how we didn't get nickeled and dimed w/ requests for all those small expensive toys and amusements... he was VERY thankful!