Well Gouvia marina itself isn't at all bad. You are resricted in that part of Greece. The Gulfs of Corith and Patras are wind tunnels in the winter and both sides are steep-to making good shelter hard to find.
Levkas is good as is ithaca but on balance I would recommend Gouvia. There are three good chandleries, the one in the town probably being the best and the owner (Peter) speaks perfect english. There is a swimming pool and a playground for the children at the marina. As well as a few good tavernas just at the entrance to the marina there is a supemarket, and a cash machine at about five minutes walk. The best food though (IMO at least) is in the marina itself. The prices are amazingly cheap. There is also a small supermarket in the marina who also keeps Uk newspapers albiet a day or two old.
Now if you were looking in the Aegean, there are lots of small boatyards offering safe winter lay-up. The one near Poros is particularly popular with Brits.
We started our "big boat" sailing at Gouvia, many many years ago, before it had a marina. We'd only ever sailed dinghies before and we'd booked a flotilla holiday for beginners and had a 33ft Feeling. We had three captains, two boys and a husband. They sent us all out to practise and it was really blowing, captains unrolled the genoa but didn't control the furling line and out it all came, the boat was flattened and I demanded to go back to a hotel. I was persuaded to continue with the holiday, with promises of "we will reef when you say so", I carried on and the rest, as they say is history. It was great to see the place again.
Over our 26 live-aboard years we have spent several in greece. Gouvia has become a bit up market to my mind and a bit overfull of ex-pat brits.
Levkas, or rather Nidri?Vliko is good but suffers from occasional sudden storms of extreme violence. Tranquil Bay is usually safe enough, but involves dinghy to get ashore.
The best and most enjoyable winters have been in Porto Xeli (on the mainland near Spetsai) This is a big harbour, but the effects of the waves that do build up on occasions are not that bad, and, because the local Greeks (with certain notable exceptions), are uncharacteristically inhospitable, the yottie community is very strong.
We have also wintered in Rodos, not that good nowadays because of the charter trade
in Porto Heli (xeli) in November. There was only one taverna open but we had great hospitality there. Looks like a good place to over-winter protection-wise but I think that "cjw" might find it a bit of a slog from Corfu>
You don't have to like the neighbours to overwinter so my first choice would still be Gouvia.
I have just comeback from Greece. Aigina All the live aboard say it was very cold this year. The place to be it is Kalamata on the sothern Peloponise marina there very cheap,good showers, and plentfull suply of good veg, they also say its very protected in the marina from all winds I have done the trip from Kerkira[Corfu] wonderful sailing Good safe stop over in Katakolon and O. Navarinou, Pilos The port captain there will not charge you if you are friendly and give him a beer, every morning he would bring wild flowers, to the boat ,and give the children a ride on his motor bike. another place to try a short stay, Methoni . New marina at Finakounda good protection there we stayed in f 7-8. DO not go to Kiparissia the swell ther is very bad even on a calm day also very large and bold Rats on the quay. if you need any more info I will be pleased to give it Cheers bob t