Personally this doesn't seem worth it. Adding in Boston and Chicago in January seems like you're just tempting the Weather Gods. What would happen if a New England snowstorm knocked out your BOS-ORD flight? I can't imagine UA is going to be very sympathetic if you miss your ORD-EWR flight because you're stranded in the wrong city and have to make last minute arrangements to go back BOS-EWR.

Plus, is saving $200 worth the fact that you'll have to get to EWR a lot (~10-12 hours?) earlier to start flying? Enjoy being able to sleep in that day and pack leisurely.