I've made my determination and our newest visitors to the feeders are male and female House Finch. There are several birds that look similar - House Finch, Purple Finch, and Grosbeak. The male Grosbeak has more red than our birds, and our book says they're a summer bird, and since it's 15 degrees out now, my guess is it isn't summer anymore. While the male House and Purple Finches are similar with their red coloring, the male Purple Finch seems to have a pointy head while the male House Finch seems to have a round head. So that's my determination, they're House Finch. Now if I can just get some better photos of them!