The wines are Chilean. Vineyards have varied in our different trips. Typically, there is a Chardonnay, a Cab and a Merlot. The sparkling wine is Kraemer (sp?) which is a nice cava.
The repeaters dinner and Feathers serve an upgraded wine. (The repeaters dinner last time had a French Sauvignon Blanc that was FABULOUS.) They also usually offer 2 white choices (chard and SB.)
IMHO, the wines are drinkable, but nothing to write home about. We don't go for the wine, and I categorically refuse to spend $30 on a bottle at an all-inclusive resort. (Not couples fault, my personal hang up.) That being said: the Cava is QUITE nice and more than drinkable, and I tend to stick with either that or Red Stripe during our stays, except when dining at Feathers.
Vee summed it up pretty well. My wife and I are serious wine drinkers and I was very concerned about the quality when we first visited CN two years ago. My worries were unfounded. The house wines are Chilean, which are generally have a very good quality/price ratio. We did not try the white, so I cannot comment on that, but for red they had Cabernet Sauvignon and Merlot. Both were perfectly acceptable and were comparable to what I would have with dinner at home on a weekday. Similar quality wines would probably range in price from $8 to $15 per bottle (retail) or $20 to $35 (restaurant) in the US depending on the store/restaurant and level of taxes in your State. I expected to pay for an upgraded bottle most nights, as we normally spend more than that while on vacation, but ended up only choosing something off the premium wine list once. That list did not have anything that really jumped out at me, and it was so easy to just opt for the house wine that I never bothered for most meals.
The sparkling wine is a non-Champagne French wine from Kraemer. It was also perfectly acceptable. Certainly not Dom Perignon, or even Moet, but the quality was similar to a decent domestic (US) sparkler like Chateau Ste. Michele. It was great for mimosas, which I had every morning with breakfast, but was also fine on its own. We had it several nights as an apertif. One afternoon our tanning was interupted by a thunderstorm. We returned to the room and called the front desk to see if we could get a bottle delivered in the rain. No problem! The ice bucket and bottle arrived within 15 minutes. It made for a really wonderful, rainy afternoon.