We've been travelling to the Orlando area for nearly 30 years (probably 15 trips in that span) and have been to Cocoa, Daytona, New Smyrna and a few others on the Atlantic side as well as Clearwater on the Gulf side. My preference has always been New Smyrna as it tends to get a little less traffic than Cocoa and Daytona, and lets you drive on the beach (less distance hauling gear). The one down side is the beach traffic but it isn't an annoyance to relaxing because the constant wind and waves drowns out any noise.
That said, Cocoa beach is wonderful and Ron John's will have anything you could want or need as souvenirs, something New Smyrna has less readily available. It's also 10-15 minutes closer. You don't mention time of year, but if it's the 2 weeks from now that your signature suggests, know that water temperatures may be a bit chillier than you'd expect. Cocoa Beach water temps are at their lowest of the year on average today (2/10) averaging 68 to 73F (65F currently). This is 15 to 20F cooler than late July highs.
If you're renting a car, you may consider just utilizing the Sunpass to handle tolls. With most rentals, a small fee covers the days you use it and bills you for the actual cost of the tolls via your credit card. That way you need not worry about getting into the correct lanes at toll boths, you simply whiz by and the license plate is read and the toll billed back to you via the rental agency.
If you have a smart phone, no need to do the GPS. If you trust your oldest (and you're patient enough), let them help you navigate by holding the phone and relaying directions. If not, take your time and enjoy what you find if you make a wrong turn. The phone will get you back no problem. If you don't use a smartphone, I would get a GPS for the car as, although things are well marked, you may get turned around. Just remember the big water is east

. Living next to Lake Michigan myself, this is the first piece of navigational advice we learned.
Gina-Gina-Bo-Bina's traffic shot is spot on unless you are really unlucky. As you get closer to the beach, traffic will pick-up a little. Just remember that most everyone is a tourist so not always exactly sure of where to go. Better to get to the beach a little late than miss it because of an accident. Unlike Disney, you get to proceed at your pace, so don't feel like you're on a deadline and you'll be fine (this is a do as I say not as I do). As far as the return trip, traffic is similar until you get back near Orlando which will be a bit hectic from 4:30 to 6:00. If it's too much for you, stop for dinner and let things calm down, you'll likely need the nourishment after a day at the beach.