How to build CRM for events in multiple years

How to build CRM for events in multiple years

I am using Zoho CRM for an event planning business. Our clients are cities, who re-sign with us every year. So every year they are a 'new' account. If they don't resign with us, we get a new client in that city. I am trying to figure out the best way to build this in Zoho. 

For example, we have an event in Atlanta every year (2013, 2014, 2015). Each year is considered a new Account, but lots of the contacts stay the same through out the years. 

I need to create a separate profile for each year, as the information, contracts, contacts etc are different for every year. However, some bits of information for the 'parent' city (Atlanta) remains the same. What is the best way to build this out? I was thinking of calling the 'Account' 'Atlanta' and then creating under the 'Potential' tab, the separate years. However, that doesn't seem like it will work because then I will creating a bunch of fields that is only relevant to a 'won' account and will clutter up the 'Potential' tab for our sales people who are in the other phases of landing a client. 

Also, would I be able to attach multiple contacts to a potential once they are won? 

Here's a little example map of what a need to create:

Atlanta: 2013 event, 2014 event, 2015 event
Boise: 2013 event, 2014 event, trying to sell them on 2015 event
Nashville: 2013 event, 2014 event, did not buy 2015 event so now we're looking for new Nashville client

Thank you!