Help Dodi Metz
I don't think that hiring a driver is necessary, unless you feel really nervous about navigating, or short on time. Renting a car might be more free and adventurous. There are also some trains, although you won't get everywhere as quickly. Anyway, if you do rent a driver, decide how much you want to spend beforehand and don't get talked into paying much more, if anything. If you stick to your guns you can usually talk people down.
If you stay in Sorrento, I would highly, highly recommend this hotel. I've hired a couple drivers and tour guides in Italy and I really enjoy working with them. In Italy, it's all about who you know, so if you have a bilingual driver/tour guide, you can discover some places you might not on your own. But, as Julia mentioned, guides and drivers in Italy are notorious for overcharging.
If you can I would suggest staying in this beautiful hotel in Atrani, 10 mins walk to Amalfi town. Travel wise just use the Sitabus.it routes. The bus/train station is only 5 mins from the centre of Sorrento town. It is cheap €7.20 for a 24 hour bus pass.