It’s said that there is no accounting for taste, so I must disagree with Dario. I found Ravello to be absolutely gorgeous. There are two grand villas, one of which has a fabulous view of the coast from its gardens. If you are there at the right time, you can catch concerts at one of the villas. The cathedral is small, but interesting. We had a great dinner at one of the restaurants.
All that being said, I do not recommend using Ravello as a base, if you are going to do any independent traveling. I usually avoid 1-nighters, but it might, in this case, make sense to stay a night in Ravello. Then you could move to Salerno, itself worthy of some of your time.
I also disagree about the utility of having a guide at Paestum. We were there as part of a day trip. Without a guide, the ruins would have looked like some tumbledown buildings and big holes in the ground.