One day in Bellevue is enough to see the city correctly if you follow a shape rather than a list. The shape is: coffee, park, lunch, garden, dinner, walk. Six anchors, five short movements between them, and no more than 20 minutes in a car all day.
Start at Bellden Café or Third Culture Coffee at 8:30 — early enough to sit down. Bellevue's independent coffee scene is one of the best on the Eastside, and the morning is the honest hour to see it. Order a pour-over, sit, and read for 45 minutes. This is not filler; the pace of the day is set here.
By 9:45 you are in Bellevue Downtown Park. The 28-acre park is Bellevue's front room — the canal loop, the Inclusive Playground, the lawn — and a slow half-loop in the morning tells you more about the city than any museum. From here, Bellevue Square is a one-minute walk, and if it is your first visit, ten minutes inside the mall's atrium is worth doing simply so you understand what "Bellevue Collection" means locally.
Lunch is the pivot decision. The two right answers are: (1) The Lakehouse or a downtown seafood room for the polished sit-down; (2) Din Tai Fung for the family/group lunch. Either is under 15 minutes from Downtown Park. Book for 12:15 to beat the rush.
Afternoon is a nature move. Choose Bellevue Botanical Garden if you have never been, Mercer Slough Nature Park if you want to see wetlands, or a 30-minute drive to Snoqualmie Falls if you want a photograph. All three qualify as "the afternoon" — do not stack them.
At 4:30, come back downtown for coffee number two at Fonté or Dote. Sit for half an hour. From 5:30 to 7:00, wander Old Bellevue Main Street: bookstore, gallery, boutique. This is Bellevue's most photogenic 20 minutes and the visitors who skip it always regret it.
Dinner at 7:30, either downtown (Ascend Prime, John Howie, or a polished mid-tier room) or on Main Street (an Italian or seafood room). Close with a walk to Meydenbauer Bay Park or Bellevue Downtown Park at dusk. That is a full, unhurried day.