I'd like to promote an underread story (not my own) that I think is quite decent:
Wings Against the Sun
Princess Celestia learns that, after a royal wedding, a Changeling invasion, and a investiture of a princess, Equestria is running short of money. A small loan from the neutral banks of Germaneigh would take care of the problem, and Celestia sends Luna and Twilight Sparkle to negotiate for the loan. Unfortunately, the Griffin Kingdom would love to see Equestria go bankrupt, and will stop at nothing to see the loan fail--including murder.
Nobody said being an alicorn princess would be easy...