Hi Michelle,
First, good news: you don't need to a buy a ticket for the 1 year old child, and you don't need to pick what parks you are buying tickets for. So the next step, how many days? When we were just at WDW over the holidays, we were there for 7 days and had a 6 day park hopper ticket. In the middle of the trip, we had one day to sleep in and visit Downtown Disney (no tickets required here). Had it been warmer, we would have spent the afternoon by the pool. So I'm thinking you may also like a 7 day ticket to have a similar plan. Once you arrive at WDW and decide you'd like to have additional days or features to your ticket, you can do that as long as you have "something" left on your ticket.
You will need to decide if you'd like the following additions to your tickets:
Park Hopper Option,
Water Park Fun & More Option, &
No Expiration Option. Of all those features, we really enjoy having the Park Hopper option to allow us more flexibility. If you'd like more insight into the add-ons, please let us know; we are happy to help.
You may want to take a peek at www.touringplans.com to help with planning your days at the parks. I love this website as it offers over 100 well-planned itineraries to help make the most of your days (more attractions, less waits). We used it over the holidays and avoided many, many long waits. It does have a small cost, but one I think is worthwhile.
Have a great trip!