I have found paying attention to shape to be helpful to distinguish between white-breasted nuthatches and mountain chickadees in my backyard. While there are definitely distinct differences in markings and behavior, the coloring is similar enough and the birds in my backyard seem to be moving all the time making it harder to catch those differences! One thing I noticed that was really helpful to distinguish between them quickly, even in movement, was the shape of their bill. The chickadees have a much smaller bill than the nuthatches. It has really helped with split second identification!
My favorite bird on the Wall of Birds was probably the Lilac-breasted Roller. I liked the folklore that goes with it. And it's pretty! Around my house, I've been primarily seeing songbirds. So far this spring, I have been able to identify mountain chickadees, nuthatches, stellar's jays, robins, and a dark-eyed junco. I haven't gotten any good photos of them though. I did see a raptor the other day, but couldn't get a good look at it. I know that we get woodpeckers too, just haven't seen any yet this year. There were a couple hairy woodpeckers that spent all last summer in my backyard.