It's really a matter of personal preference and cabinetry size/style. Posting a photo would help to provide more specific suggestions. :)

It's your choice, and there are countless sizes of pulls (some will be in inches, others in millimeters). Most pulls aren't under 3" wide (and if they are they'd be more for a furniture piece than cabinetry). If it was my kitchen I'd avoid the combination of knobs on the drawers and pulls on the doors, it looks backwards.