We enjoyed our 7 night cruise from Athens to Istanbul. It was our 5th cruise with the ship. We probably would not sail unless it is a Regent cruise.
The staff and crew are always professional. The ship was spotless. The food has improved since our last visit on Voyager. Even the entertainment has improved. There are a few things, the Canyon Ranch, highly overrated in North America, is about the same on the cruise ship. Prices are outrageous for the type of service and the staff seems preoccupied or bored. But tourists needs spa treatments and so we used our ship board credits at the spa. Our room was spotless and the attendant tried very hard to get the linens right without using down comforters and pillows. The ports were all very interesting. Tours are nicely organized although the tour quality has deteriorated in some of the ports. It's hard to give feedback to the tour desk and they don't seem to care about the level of satisfaction as much as they used to. But Regent has a new corporate owner and despite three owners since we started as customers, overall it's still a great value.
If you enjoy cruising, you might pick a cruise that includes day at sea to recover from all the excursions. This would give you a chance to enjoy the ship's amenities. We have always enjoyed the expert talks that Regent provides although I think the number of ports prevented the talks from being held. We missed that.