Stay in the C/T or Santa Margherita Ligure?

If you have never been at the Cinque Terre, I would stay in Monterosso, the largest and westernmost of the 5 (cinque) villages. From there you can take trains to the other cinque terre, or go to Santa Margherita in 45 min. by train. It's not mandatory for you to hike at the CT. I've been there countless of times and I hiked only twice in my life.
Another smaller place I liked in youth, was Moneglia, a small resort town between Levanto and Sestri. Santa Margherita is a bigger town, once you add Rapallo and Camogli next to it, it's a pretty size city. I prefer smaller places in Liguria.

We stayed in S.Margherita and loved it. It was handy to the train, so you can plan exactly how many villages you want to hike. It is also close to other Ligurian towns (for strolling and people watching). Depending on the time of year, the villages can be quite crowded, which was the attraction of SML for us. We stayed at a small (and reasonable) B&B, Villa Gnocchi, which was up above the actual town in a lovely setting with beautiful views of the coast. I seem to remember that you could also get a nice dinner there. We did have a car which made it easier to get into the hills above the town.

I would recommend staying in the C/T. About 10 years ago we stayed in Santa Margherita Ligure and did not enjoy it nearly as much as the actual CT towns that we stayed in on earlier trips (Manarola and Vernazza). I think Monterosso would also be a good choice. We took a ferry one beautiful day from Monterosso to Porto Venere .... gorgeous trip .... highly recommended.

I would also recommend staying in one of the CT towns rather than SML. The CT towns are smaller and more quaint. I love Monterosso and always stay there because it's the largest of the 5 towns, the flattest and has the most options for restaurants, amenities, etc. It's really easy to get between the 5 towns via train or boats (if they're operating). We didn't hike between towns on our first trip and simply enjoyed visiting each town and walking around taking pictures, etc.

As for a hotel suggestion for Monterosso, if you can snag a reservation at Hotel Pasquale, you can't go wrong! All the rooms have ocean views and the hotel is close to the train station. The rooms are very clean/comfortable and the rate includes a nice breakfast buffet complete with warm homemade croissants every morning filled with marmalade! The proprietors are very friendly and helpful. It's a popular place so you'll likely need to book in advance. Have a wonderful trip.