DO NOT propose the same weekend as the inauguration. You would be stealing the show from her dad, and whether he acknowledges it or admits it, it will bother him. That would be cheating the family and, ultimately, yourself.
As for the ring, I'm all about spending as much as you possibly can. She will have it for the rest of her life and you will only regret it if you skimp out on it now (adding onto it later, which a lot of people do, is incredibly tacky). Plus, the bigger the ring, the further away other dudes will stay.
