SunPass is definitely the way to do it if you are a frequent visitor to Florida, especially if you plan to head south to the Miami area where a lot of the toll roads are already Cashless.
Keep in mind that you have to purchase the SunPass Transponder ($20) and open an account with a minimum balance of $10 and setup some kind of top-up for the account (CC) when the balance drops below a certain amount, so you will always have money tied up here. If you use the SunPass frequently (more than 40 tolls), then you get a discount off the toll cost.
However, most of the toll roads that you will need to use in Central Florida (from MCO to WDW or offsite hotels) use tollbooths where you can pay cash (about $4 total from MCO to WDW).
So, if this is your first visit in a few years and you may not visit again for several years, you could probably forgo the SunPass Transponder and just use the Cash lanes.
This may change in the future as more of the system becomes Cashless (SunPass only)
With 55 million+ tourists per year coming to the Orlando area, I'm sure that the toll road from the airport to the tourist areas will be the very last to convert (if it ever does). There's just too many tourist dollars at stake to alienate those folks.