We put our D80 in our Baggallini messenger and it was fine/great. It was easy to swing the bag around to grab the camera.
We never take our whole wallet into the park--just a CC/DC, license, and our KTTW cards. That leaves plenty of room for sunscreen, autograph books, the DSLR, etc. We keep the sunscreen in a zipper bag just in case. There is a pocket on the outside for a bottle of water.
I also bought a neoprene case that fits my DSLR exactly (I leave one basic lens on) and this helped pad it a bit.
At bagsbuy.com *save10* will save you $10 on the bag, no shipping, no tax and you'll get a 10% discount for registering, making the bag @ $25--get another $5 back through Mr. Rebates.
I used all the codes TODAY and they worked fine.