You got it!

It was only about a $90 difference in price to get the fully refundable (to original form of payment) ticket so I thought it was a pretty good deal to book that way in case of a fare drop. In all, from when I booked to what the fare is today (on the same fully refundable ticket), it has dropped by almost $300 and I would much prefer the actual refund vs an e-voucher. A refund never expires, the e-voucher is only good for 1 year from the original purchase date.

On Delta you are looking at Basic fare (pretty much no changes and seats assigned at check in), Main cabin (cancel/change with e-voucher/eCredit) and Main Cabin fully refundable to original form of payment. You can also book Delta Comfort+ and Delta First Class. Each level adds a premium to the base fare. I initially chose the Main Cabin Fully Refundable.