I think HSA Bank is a good option, reasonable fees and gives you the investment option if desired.
Another option is to find a local bank that has reasonable fees and interest. Develop a relationship by sending them referrals and ask about doing some joint marketing, maybe a seminar for their clients concerned about their health insurance premiums and present the HSA as a possible solution.
Two places I believe to be better options are Bancorp Bank and Health Equity. They both offer investment options and have low fees.