If you decide to go the trailer route the Croozer dog trailer that Smurf mentioned above are nice. One of our fellow TE sisters has one which we got to play with at a TE gathering. Her Croozer(older version) can be used with the sides folded down as a flat bed cargo trailer sans doggie.

Child trailers are nice in that you can pick up a used one pretty cheaply and most of them have a compartment in the back for groceries/gear. I think Burley has the most rear cargo storage but their resale prices tend to be higher.

I have a Chariot child trailer for DD, which I love, but it doesn't have a lot of cargo capacity - no zippered cargo compartment like Burley, just a pocket and shallow cargo tray in rear. However, it is easy to attach a backpack to the handle bar if I need to carry more than the cargo pockets can hold.

Here's the thread about it:

http://forums.teamestrogen.com/showt...roozer+trailer