Assuming you're staying at the Grand Vista you can get a good cup of coffee and normal quick stuff like burritos at Octopus Coffee across the street. Address: 759 Horizon Dr, GJ, CO 81506
Another option if you're on top of schedule and have time for diner-speed can do real breakfast at First Watch, which is at 1st and Patterson not far from the Masonic lodge. Address: 20 W Park Dr, GJ, CO 81505
Bring a lunch, you can't count on time to get it. Kind of depends too on how fast or slow you guys move.
If you need to stock up there's a Safeway at Horizon and 12th St, about a mile west of Grand Vista. You can see the new Mormon temple in all it's blistering white marble beauty, too. Address: 681 Horizon Dr, GJ, CO 81506
In the event you have time to get lunch near the Masonic lodge there's a new-ish place, Great Greek, on Patterson that is pretty good. Address: 2566 Patterson Rd, GJ, CO 81505
Otherwise it's kind of a desert up there. McAllister's Deli is close to the First Watch. I'd suggest 7th St Deli, across from St. Mary's hospital instead, if you have time. Address: 2232 N 7th St, GJ, CO 81501
Other options, dinners, etc. Let me know preferences, if you want more recommendations.