I use Fidelity for my rollover Roth and traditional IRAs, and then also savings and checking, and think they're great. I can't offer much in the way of investment-specific advice, but can tell you that they have a lot of commission free ETFs and funds. If you're buying a few large blocks, then that probably won't largely factor into your selections. One other thing - the investments you purchase through them do not automatically reinvest dividends. It won't cost you anything to do that, but if you'll want to check to make sure that option is chosen.
Best of luck!