Hmmm well it depends where you want to stay. The hotels Bitacora & Vulcano consistently receive good reports in Las Americas, especially for the food, as does hotel Arona Gran in Los Cristianos, all part of the Spring group of hotels. I like the Gran Tinerfe in Costa Adeje. These are all mid price range 4 star quality hotels within walking distance of beaches etc.
Where do you want to be resort wise?

Well we were thinking about Playa de las Americas, but have been told by a friend that it's very touristy and a bit like Benidorm, though whether that applies to October I don't know. I've seen the reviews for Vulcano and were very impressed by them.

The Costa Adeje end of Las Americas area is very nice. Lots of 4/5 star hotels.

I think playa de las americas is very much touristy. but the beach is wonderful :-)

Don't think you can really go far wrong either at Costa Adeje/Fanabe end of Las Americas or the other (Los Cristianos) end and of course it's "touristy", its a tourist destination! One of the top all year destinations in Europe.
Having said that, Tenerife has something for everyone and is a wonderful place to holiday.
Don't go with any pre-conceived ideas about anything, just enjoy.
Unlike Benidorm it is truly a year round beautiful climate so is as busy in winter as Summer, difference being that in winter you have the longer term tourists from all over Europe who come to escape their winters so the age group is higher then on average.
You have lovely beaches, amazing trips and can walk along a lovely pedestrianised promenade from Los Cristianos to La Caleta, a fishing village other side of Las Americas. There is nightlife if you want it but if you dont then you can just take an evening stroll and feel safe, there are local markets and proper Canarian streets and harbour at Los Cristianos plus many other local towns and villages all a local bus ride away.