I am a very stripped down, be prepared kind of packer.

Minimal stuff, maximum impact.
We always have with us:
--An action pack (gallon ziplock with two diapers, one old receiving blanket, half empty or travel pack of wipes--air squished out to save space--I have these EVERYWHERE at home--cars, strollers, purse.)
--one light weight, weather appropriate outfit (in a ziplock (just in case you have a mess and need to pack the old outfit into the ziplock) mesh for summer is gr8!, but light weight long pants and ls shirt is good if you are going morning or evening. Babylegs are also good for changes in weather...take up little room, but can help chilly arms or legs. Socks!! They can help thwart blisters or cover chilly piddies and take almost no room.)
--swim diaper, trunks or suit
--one old, clean altoids tin with bandaids, a safety pin or two, dum-dum lollipop, individual pks of meds for DH and me, kid pepto, neosporin pks, rubberband for my hair, moleskin...you get the idea
--a bandana (usually tied to the stroller to make it easy to spot, but also ends up being useful for lots of odd little things.)
--sunscreen in a ziplock
--take & toss sippy, spoon and fork
--antibacterial wipes (small packs of wet wipes so I don't have to get into the diaper pack)
--camera, batteries (in a ziplock--notice a theme here?)
--a muslin receiving blanket (makes a surprisingly good, quick drying towel! Really!!)
--matchbox cars!!!! (I always have a few on me--there are Mickey Mouse ones I have stashed for our next trip.)
--snack--I try to take as many different snacks as there are planned hours to be somewhere (4 hrs out in the world, 4 different kinds of snacks). May sound fiddly but it helps me plan. Freeze dried food is really light weight and nutrition packed--yogurt, peas, corn, mango. Also a fan of the squeezy astronaut baby food packs (veggies!). Earths best rice crispy treat bars are awesome and hold up to squishing well. You can use old puff containers to hold fruit that can bruise easily (bananas, pears, plums...)
It may sound like a lot, but I can easily fit it all into a small tote (reusable shopping bag size) with room to spare. If there is room I'll throw in glow sticks, more snacks, more snacks, more snacks...

For this trip we're planning to use an umbrella stroller with no storage and one of those string backpacks.
I always have to remind myself that we are not venturing into the Yukon, we're just headed to the park for the day. They have just about everything we need (for a price, of course...).
