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I agree with Hutch re-targeting/re-marketing does help, we tried adwords/facebook/adroll/criteo depending on your target CPA some maybe out of question, in my experience the cheapest is adwords, but it doesn't have the largest reach. Based on my little experience I am also very much skeptical about all those cart abandonment packaged solutions, the real improvement is negligeable. In my experience A/B testing like mad (ux, copy, discount, exit popup, etc...) is what really bring double digit improvements. But I do agree with Ryan, a professional CRO company (like http://www.conversion-rate-experts.com/ seems to be, but I never tried their services) would probably help identify what to test and shorten the time required to get results.

The best way to handle this, for all crawlers including Google, Yahoo and Moz, is to make sure you have proper canonical tags on those URLs that point to the non-parameterized URL. So http://www.example.com/example-product.htm?ref=navside will have a canonical that points to http://www.example.com/example-product.htm

Hi Tim, Thanks for coming to Q&A with your question, which is a great one! I'm the Local SEO Associate here in the forum. Members are giving you some good suggestions. I'd like to add to this. I strongly recommend that you put more effort into your city landing pages than what you are describing. 4-5 sentences is really just a blurb - more like an intro than the content of a whole page. I recommend that you find more to say about each city in which the client serves than this. Then, if you have in the midst of this, a small list of the client's services/products, only a tiny percentage of what is on the page will be similar. Creating city landing pages is one of the most common tasks I accomplish for my clients, and I treat each city as being deserved of a full article. It's an approach I have seen work time and again and I highly recommend it! Hope this helps and best of luck! Miriam