This is where we got engaged! A fairly easy ~3 mile loop (easy for Colorado at least).
A cute, downtown walking mall with plenty of shops. For food we recommend Gelato Boy, T/ACO, Organic Sandwich Company, and Mountain Sun (CASH ONLY). At this time of the year there should also be lights up for the holidays!
One of our favorite date spots in Boulder, that also has a good brunch option. Other brunch location favorites include Le French Cafe, Walnut St Cafe, or Snooze an AM Eatery.
If you are feeling ambitious, and depending on weather, you could consider going to the nearby Eldora Mountain to ski! There is a bus from Boulder up to the resort (NB1), and it is only a 40 minute drive away up the canyon (past the wedding venue!). It's not uncommon for Boulder locals to ski a half day on a Thursday before going to work.