There are several bonuses to pick up along the way here. The Doctor of Credit blog keeps up-to-date links.

I think the best order is something like:

1. Merrill Edge opening bonus first, $1000 for a $200k transfer
2. Bank of America checking account, see if you are targeted for the $300 opening bonus, else take the $100 public bonus
3. Enroll in Preferred Rewards as soon as it allows you
4. Premium Rewards Credit Card after your Platinum Honors status is recognized, so you get the additional bonus on the signup bonus in addition to the spending points (edit: no boost on the signup points but you do get it on the earnings to get to the signup)
5. Possibly then re-finance your mortgage. If you already have Preferred Rewards, you should get the mortgage origination discount, then you can transfer in additional net new funds to the Merrill Edge account to trigger up to 0.375% off the lowest rate you can otherwise negotiate (many reports of people seeing rates under 3% this way)
6. Also possible to be targeted for Savings bonuses up to $500 and Business Checking bonuses up to $750 throughout this process

Can be a very lucrative relationship...