I was a definite paper person, but was constantly split between the great size of the 8.5x11, the "grabability" of a 5x8 notebook, and the "stuff-in-your-pocket"-ness of 3x5 cards.
I could not brainstorm or mindmap with 3x5 cards. I did not like carrying a clipboard with me into the gas station or to dinner, and I didn't like rewriting everything to different sizes.
My solution? I finally settled on... a smartphone. It was the only way to carry the volume of information I needed all the time without needing to carry around briefcases and binders everywhere... even my Contacts list was 25 pages long, in 6 pt type.
However, while I use Outlook for tasks, etc., I often print out my Task list and calendar and grab a clipboard if I have many errands at once.
A good thing about 8.5x11, even if not on a clipboard, is that it can easily be folded and tucked into a pocket or wallet.
I still use 3x5 cards for nearly all capture.
Rewriting is never an issue if I just have to print out a new page or two... take seconds.
If you definitely needed to stick with all paper, I would recommend a clipboard and a few report binders. The clipboard is for NA lists (which can be folded and tucked into purse, pocket, etc.) and Calendar, with some blank pages to spare. I would then get either several thin report binders or one big honking 3-ring binder for all of my Lists, including Contacts, Projects, etc.
I would take the big mambo binder with me every time I got in the car. Carry it home, leave it inside. Carry it to work, bring it in. Carry it to the movie theater, store, doctor's office, or restaurant, leave it in the car. That way, it's always accessible if needed but without the bulk.
I did this by leaving the binder in my briefcase, which would go with me in the car everywhere.