We have on our to-do list a new feature for showing more thumbnails under People, Suggestions and Unknowns.  

This may also include the ability to change the thumbnail size, although we believe the main request is to "show more"!

Example; we are grouping Unknowns by cluster - and if the clusters are less than 5 it is not a good use of screen real estate.  So our plan is to show a continuous feed of unknown faces, sorted by cluster, so you will be able to show fairly large groups of thumbnails at one time.  We want to balance the load time and scrolling time for these pages.  But, the upper limit will go up to 250 or 500.

Stay tuned!