Corpus Christi is currently reviewing apps. Received a rejection from them today because of board scores. She advised me that they have a very competitive applicant pool this year. Also have a friend who received an acceptance from Maricopa today so they are reviewing apps too. Accepted to Baystate yesterday.
For the letter of interest I just state the specifics of why I want to rotate at their program. For me this has been boiling down to ties to the location, knowing someone who did their residency at the program, any relevant cultural/demographic ties, unique fellowships they may offer that I'm interested in, etc. If I'm struggling to find information on them off their website then I usually do a search on here for experiences/comments on the program (esp that spreadsheet we have).