It's a small town - there aren't many Estes Park grocery stores. But it's a tourist town, so at least what we have has a decent selection.
Safeway 451 E Wonderview, (970) 586-4447 This is the main grocery store in town, and part of a large chain. They have everything you'll need from a grocery store, and they'll have lots of people and lots of long lines! They also have a bakery, a deli, a pharmacy, a Starbucks, and photo developing. For sanity, I recommend shopping early in the morning or late at night. Any other time of day will raise your blood pressure. During the winter, you can go anytime.
Country Supermarket 900 Moraine Ave., (970) 586-2702 This is a small, locally owned grocery store near the main entrance to Rocky Mountain National Park. They tend to be much less crowded than Safeway, but the prices are slightly higher and the selection somewhat smaller. Small prices to pay for sanity and relaxed shopping, in my opinion! They also have a bakery and cafe and they are in the same complex as a gift shop, restaurant, gas station, and liquor store.
Estes Valley Farmer's Market 470 Prospect Village Dr., (970) 532-4581 Open Thursday mornings during the summer, the farmer's market offers fresh produce, breads, cheeses, smoothies, flowers and more from area farmers. Next to the Estes Park Brewery.