95 isn't all that bad above south Florida in my experience. We use the turnpike mostly to avoid the big metro area traffic further below Jonathan Dickinson area when we head to the Keys.
The Sunpass is worth having if you plan to come to Florida often for the small toll saving and the convenience of shooting through the faster lanes.
In some places, there are no longer toll booths, so cameras read your tags electronically and if you don't have Sunpass, they mail you a bill. Then you have to wonder when it will show up weeks later, and be around to pay the paper bill.
We have family in Florida and go often in car or RV, so use the system often. If this is likely to be a one shot trip, I wouldn't bother, though. You'll end up with leftover credits on your account.