The fall marathon season usually has plenty of options with all the races everyone has mentioned: Chicago, Philly, CIM and Houston.
It's the spring that's a struggle for OTQ's to aim for. Boston has great potential as it's a well supported course, but the weather is a huge gamble. Same goes with Grandma's. It;s a great course, but the weather is the limiting factor. If more people can get together and coordinate a spring race, then there's a good chance for some quality OTQ's. I'm planning on making an attempt at the 2:19 time standard, so this is what I got in mind. And for reference, I ran 2:17 at CIM to qualify for the trials. Then got a bunch of stress fractures in the past few years, recovered and recently ran a 2:25 at CIM this past 2017.
Currently the best options are:
Fall 2018 - Philly (the course is fine, but the time of year makes for optimal weather, cool temps in late fall)
Spring 2019 - Boston (good course, support and depth, but variable weather)
*Spring 2019 - Grandma's (back-up race if Boston is garbage)
Fall 2019 - Chicago (good course, support and depth, but again... weather could be slightly warm/hot)
*Fall 2019 - CIM (back-up race if Chicago is garbage)