Would be great if I could select multiple modules to apply a smart rule to, rather than having to do each module in an email individually. When you're customizing a lot of different modules at once (basically serving up dynamic content to two different audiences, or more) this would save a ton of time rather than having to apply the same smart rule over and over to different modules.
2) Workflow/List Logic
Would be great if logic for workflows and lists were more customizable. I find the AND/OR functionality quite limiting and sometimes have to run multiple lists to get to the logic I'm ultimately seeking. Would be great if you could get more customized - an equation style workflow would be much better for things that are a bit more advanced/complex - ex. (A AND B) OR (C AND D). Marketo has this ability and it is quite convenient.
