I made some scale drawings comparing using all 7 inch bar pulls vs, going proportional. That helped a lot.

A good rule of thumb is that the pulls should be approximately 1/3 of the drawer width. It's an eye-pleasing proportion. We have 3 different sizes of drawers so have 3 different pull sizes for them.

I agree with Vinudev_liny - can't beat the mock-up for helping decide. We used the heavy cardboard from the boxes the cabinets came in to make the mock-ups. The pulls we liked came in 10 sizes or something like that. I cut the cardboard in the pull shape and about 5 different sizes we were considering, and held them up to the drawers and cabinets (we also used the pulls vertically for the cabinet doors). Made the decisions so much easier.

I guess you could say I went against the grain because all of our pulls are standard 3" pulls.

I thought about doing different sizes but ultimately decided I preferred the look of them all being the same.

Bonus for me is that if I decide to change pulls in the future to upgrade the look, I won't have to search very hard.

I've been mentioning the Golden Mean, or rule of thirds, for a few years. I have several size drawer stacks, and used three different size pulls to generally follow this rule. I ordered more pulls of each size than I needed and held them up on stacks to see what looked best to my eye. Then I returned the overage.

I'll link one thread below in which the a Golden Mean has been discussed. If you run a google search for this site, (i.e. site:gardenweb.com breezygirl golden mean), you'll find more. Good luck!

Here is a link that might be useful: One Golden mean thread

I listened to breezygirl and used the rule of thirds as much as I could with the handles I chose.