I had all my photos printed at Costco which gives you the option of some larger prints. Ie: 12x20.
I also mixed up the color with black and white. I also love the look of a smaller print inside a larger frame. I took all the glass out of the frames so there was no glare, and used masking tape.

thanks that helps I'll go to Costco. How did you use the masking tape - to hold the pics in the frames?

You might be able to get this look too by using mats. Buy larger frames, maybe 11x14's or even larger and use matting in a coordinating color to help from your 8x10 inch photos.

I agree on Costco- great prices for printing and for frames! Yes, definitely use a variety of sizes, but try to create cohesion by using similar frames/matts. I did a similar family gallery wall that also has both black & white and colour. The frames are all black of different thicknesses with crisp white matts. You could always spray paint frames....

Easy way to do the layout---take paper bags, trace your frames that you'll be using onto them, cut them out. Then use tape to move the paper "frames" around until you like the arrangement. Once you like the effect, then hang your frames. Saves unwanted holes in the wall. :)