Thanks Heather. That tells me what I need to know.
It sounds as though you aren't considering high mountain trekking, and that is good, because it would be completely unsuitable for you, and risky. The conditions in the Lefka Ori are nothing like those in the Lake District: they are much more extreme. The peaks are almost three times as high, for starters, and no-one who isn't familiar with them should be attempting them without a guide, even in summer, and certainly not in autumn. The summit treks are full of sink holes where it's easy to come to grief, and the weather conditions can be very treacherous, even in high summer. October is no time to be there unless you are with a guide - or you ARE a guide.
You can't "explore the mountains". There are no roads in the mountains. As I said, it isn't like the Lake District, where the highest peaks are around or just over 3,000 feet. The summit of Pachnes, the Lefka Ori's highest peak, is 2,453 metres - well over 8,000 feet.
So we'll leave that one. :-)
Chania is Crete's most beautiful city, and certainly one of the most beautiful and interesting cities in the whole of Greece. If you're still open-minded about where to stay, I would certainly suggest you stay in or near Chania, rather than in Kissamos. There are good hotels everywhere along the coast. The closer you are to Chania, the closer you are to Chora Sfakion and Loutro - and for accessing the Samaria Gorge if you want to walk it. But if your wish-list of west coast beaches includes Balos, Falassarna, and Elafonisi, as I'm guessing it does, you'd be closer to them in Kissamos.
It's up to you, of course, but there are beaches everywhere in the world and in Crete, and I'd be wanting to see what Crete uniquely has to offer, and Chania would be on my list, very near the top.
On the coast it should be warm enough most of the time - except when it rains, which it may - for shorts and t-shirts, and unless you're really unlucky with the weather, you'll be able to do plenty of sunbathing. It will be cool in the evening, and you'll be eating outdoors, so bring something warm to put on.
If this is going to be mainly a beach holiday, I wouldn't consider staying in Omalos or Anopolis: both are a long way from the sea, and will be much cooler than anywhere along the coast.
Loutro is nice: there is plenty of good accommodation, so if you want advice about that please ask me. Loutro's beach is small and very busy in the season, but it shouldn't be too busy in October, and as it is one of the warmest places in Crete, you should be fine there. There are much better beaches an hour's walk to the west (Marmara) and east (Sweetwater). In the summer there are daily boats to take you there and bring you back: they will probably have stopped by October, but both walks are splendid coastal walks. Loutro is in fact the best centre for walking in the southwest, which means the best walking in the whole of Crete, and in October the air temperatures are perfect for walking.
I hope this is helpful. If you have any more questions, just ask.
Edited: 1:22 pm, June 23, 2013