Steph C.
Yelp
If you're visiting Sapporo, chances are good that you'll make use of Sapporo Station. It's a great train station, central and easy to access, well organized and clean and even quite pretty.
It's a straight shot from the New Chitose Airport. I'd definitely recommend taking the train in instead of paying for a cab. You can buy reserved seating, but this seems unnecessary, especially on the way in, as the airport is the last stop and it isn't hard to get a seat in an empty car.
Sapporo is a major station, so it's got lines heading out to all kinds of places. We took little trips to Otaru and Noboribetsu during our stay, and getting there was easy, just quickish train rides out of Sapporo (well, plus a short bus ride from Noboribetsu to our hotel).
Customer service was polite, and we were able to purchase our train tickets both at the machines and at various counters without issue. The only thing I'll note is that you might want to plan ahead a bit if you're getting on a smaller train. We had to wait an hour or so to get our train to Noboribetsu, as the one we'd planned on catching was sold out.
The station wasn't a bad place to kill some time, though. There was a whole shopping center in there with a bunch of stores and several restaurants. We ended up dropping into the bookstore for a minute then eating parfaits at a place called White Cosy.
So when in Sapporo, I'd highly recommend traveling by train when you can't get around on foot. Sapporo Station is central and easy to figure out, and you can get your shopping and eating done there too.