gd,
Most of us here have a favourite of the five towns, and my preferred location is Monterosso. It's the largest of the five and therefore has the greatest number of accommodation choices, restaurants and other tourist amenities, along with the best beaches. It has an "old town" and "new town" areas so it's possible to find quieter areas. It will probably be a bit quieter in October but still vibrant in the evenings.
ALL of the towns are "touristy" to some extent, but more so in the "high season". I suspect that "touristy" won't be as much of a concern in October.
If you want "less touristy", then Corniglia would be the obvious choice as it's the least favourite of the five, mostly due to it's location. It's on the top of a high bluff which means visitors have to either take a shuttle up from the station, or climb hundreds of stairs. One important point to consider is that some/all of the tourist facilities there may be starting to close for the season in October.
I've never stayed in Vernazza or Manarola, but those are also good possibilities. Riomaggiore is nice, but it tends to be somewhat "quiet" in the evenings (probably more so in October).
There's little point in offering hotel and restaurant suggestions before you've decided which of the five towns you'll be staying in. I can only offer suggestions for Monterosso.
A few final points to mention.....
- Depending on when in October you'll be there, weather could be an issue.
- I'm not sure when the Ferries discontinue operation for the season, so those may or may not be available while you're there. Their operation is dependent on weather, so if the weather is bad they won't be running.