I am more than happy to vouch for the gastro department at Mayo Clinic, Rochester, from personal experience!!! And several other departments as well! Mayo is the EPITOME of efficiency, yet "bedside manner" is as important as well. The entire town is such a friendly, helpful town. My family and I have been going to Mayo, Rochester, for some 50 years despite it is a 12 hour drive for us. The town itself is losing some of its wonderful charm due to outsiders and chains buying up the local businesses but its still "the" place to go if you aren't getting any satisfaction w/your health care at home. I was Dx'd at Mayo, Rochester, in 1976, had my emergency resection there in 1978 and return there as needed. I was just there in October of 2008. If you have the option of going to Mayo, Rochester, GO!!!!
There is also a Mayo Clinic in Jacksonville, FL and in Scottsdale, AZ. I've never been to either one so can't personally vouch for their gastro departments.