I am interested in references of agencies that build email and landing page templates. Specifically email and landing pages that are graphically/visually fresh but are also easy to modify, view well on all browsers and are optimized for mobile. Any suggestions?
You can also check out the Marketo Launchpoint site. There are agency-managed services from Marketo partners listed there. In terms of designs and resulting products for the handoff, just make sure you have a result that a team can deal with. Some designs are downright difficult to replicate and then change/update in Marketo's editor itself. Responsive Marketo landing pages can be difficult to create/maintain as well, since the WYSIWYG editor isn't quite designed for it.