The bus system on Syros is very good and quite regular.
The area between Finikas and Possidonia (where we stayed) is very attractive. A lot of people stay in Kini (a shorter bus journey to the port/capital). Galissas would be another good choice.
The buses basically do a loop, connecting the capital Hermoupoli with all of the coastal areas where you could stay. When we were on Syros in September, Kini was included in some of the island bus 'loops', though I had thought that the Kini bus only went to and from Hermoupoli.
Hopefully someone else can clarify the Kini bus schedule. If it is not normally included in the island bus loop and you are reliant on public transport to visit other beaches from your 'base', then one of the other locations may suit you better. Kini, however, is very pretty and I understand why it's so popular.
Kalispera Lucy, it depends on what you want, hiking, beach holidays or rather vacation in a city?
Syros is an interesting island, with an interesting story. The capital Ermoupoli is a pleasant untraciated city. Syros has its own charm.
Very interesting is the north of the island. Ano Meria (the highlands), which is very untouched and originally. Hardly populated, there are only a few small hamlets and beautiful from the countryside.
There are also a few nice walks here. Also to the lonely beaches on the west coast. Between the village of Kini on the west coast and the Cape Egremos there are many lonely beaches, e.g. Ghria Spilia, Lia, Aetos and Varvarousa. In the map Syros (10.22) 1: 20,000 of Anavasi are all hiking trails.
In the original hamlet of Papouri, there are the tavern t <Áloni and the also original hamlet of San Michalis the tavern to PlacoTroto.
The area Ano Meria has impressed me scenic. Very nice for the eye. The island's center and the south (Mesaria and Voi) did not like me. Is too crushed to me like a Swiss cheese. The places and the countryside have no charm.
Kalo Taxidi, KV
As said public transport is very good. I suggest to stay at Ermoupoli (Hermoupolis) a very elegant and beautiful town by the harbour.
Kini is nice but very small place, without character.Edited: March 25, 2021, 3:00 am
We had 5 nights on the island last September - we spent 2 nights in the main and buzzy town of Ermoupoli and then 3 nights in the small fishing village of Kini - that was a perfect balance for us. We also didn't have a car and used taxis to get to 2 different beaches when we were staying in Ermoupoli and to and from Kini. I think each journey was €15-25.
This gives a good summary of the different areas
Thank you for your response. Does the main town have a nice drinking atmosphere for wine / cocktails?
Most famous beaches where you can go by bus, like Galissas, Kini, Azolimnos, they are nice, not something very impressive, but nice...
There is also Ermoupoli small beach.
You can find enough places with bar atmosphere by the port (Ermoupoli) and the interesting old town ( Ano Syros) or the area Vaporia or the Town Hall Square...
Vaporia is a beautiful area to stay, the most romantic
The food is excellent in most of places.
Syros is elegant!Edited: March 26, 2021, 3:42 am
The main town on Syros is one of the most cosmopolitan non-tourist places in Greece - with good high end restaurants and cool places for drinks/cocktails - and a lovely buzz/atmosphere. It's very modern Greek.
The beaches are nice - the one at Agathopes has this beach club:
And De La Gracia on the same beach is great too
This video covers all of the island - skim through it for a look at the main beaches of Kini, Galissas and Agathopes https://www.youtube.com/watch?v=KAk-ZiEuk_g
As you have now said that you are looking for a beach holiday on Syros, here are a few things to consider.
Most of the beaches on Syros (Galissas being one exception of which I'm aware) are narrow, with the main coast road running directly behind them.
Kokkinos, in post 2, is recommending beaches and walks in the north of the island. However, there is little or no tourist provision north of the road that runs between Kini and Ermoupoli and certainly no buses.
You state that you like walking, but I don't know whether you mean exploring on foot (for which the capital Ermoupoli is ideal) or if you mean walking on an island's old footpaths.
Perhaps there are some in the more remote north, but from what we saw in the more developed south of Syros, it is not an island for walkers, unlike, say Amorgos or Naxos. There appear to be no waymarked walking trails in the south, which is where you would want to stay. We did manage to do a walk between Finikas and Galissas, but most of the walking that we did involved walking on roads, some of which can be busy.
If you are set on a beach-based holiday, choose one location from the info on the link that Paul S has provided you with. You will then have the option of spending one or two evenings in Ermoupoli, using the public bus. This in when the city really comes to life. It's very quiet in the afternoons but it can also be extremely hot then for exploring.
As far as I am aware, there is no sandy beach in Ermoupoli. The locals and visitors use the pontoon by the Asteria Beach Bar in the beautiful and impressive Vaporia district of the city.
The "best" base is probably a matter of opinion; but it does not matter that much as Ermoupoli is well-connected, and a relatively short distance from beach villages such as Kini and Gallisas). I have stayed in both (i.e. Kini and Ermoupoli) separately and have also combined the two on my stays on Syros. Nowadays, I stay in Kini (I disagree totally with post #3, as I find it charming and relaxing, and I prefer it to Gallisas) and go into Ermoupoli as and when I feel like it, as it's a very easy bus or taxi ride away True, the beaches on Syros are not particularly spectacular in comparison to certain other islands; but they are pleasant enough to spend time on, and eating in the tavernas at night. There are nice walks around the coast from Kini, too.
In response to your 2nd question; Ermoupoli has a fantastic atmosphere at night for eating / drinking, with a very large choice of restaurant and bars. "Modern Greek", as Paul S has described it above, is a very good description. It's an interesting and beautiful town, that is just "large enough". I love swimming there in the day, too, against an unusual backdrop of Neoclassical buildings. There are not great numbers of overseas tourists on Syros, and it's definitely one of my favourite islands.