I've actually been meaning to write something about this for a while. This is the quick and dirty version.
All these ideas are assuming it's sunny/not raining/pleasant to be outside (which is a big assumption).
Probably my favorite spot in the city. I think exploring Pike Place, especially below the main drag is really fun. Similarly, go check out shops in the Alley. There's a new developed space on the far-west side of Pike Place that has long steps meant for sitting and looking along the water. Perfect for lunch.
Some favorite bites: Le Panier is the 2nd best french bakery in Seattle. Storyville Coffee always feels like you're entering a speakeasy cafe. If you go on Sundays, there are free chocolate cake slices (and they don't skimp on the portion size! It's deliciously free). Meesum has quality buns there. Pike Place Chowder actually lives up to the hype and has the best clam chowder in town.
After Pike Place, I love moseying down to the waterfront near the aquarium and waterfront stores. Frankfurters have the best hot dogs in town. Ivars is a classic. My favorite table seating on the waterfront is on the south side of the pier that has Elliot's Oyster House. You have to walk past the outdoor seating with red umbrellas, and it looks like a private path, but it's actually public. You'll see a row of tables that border the south side of the pier all the way to the back. I've never not found an open table. Gorgeous views of the water, ferris wheel, and the Argosy Cruise boats coming and going.
After time there, you can swing north to the Olympic Sculpture Park and even keep walking into Mrtyle Edwards park (which is seriously underrated and feels like the most locals-only park in Seattle in my opinion). There are small cute beaches there and if you keep walking north you'll hit this brand new beach that Expedia built for public use. Really cute vibes with seating, grassy steps, and sandy beaches. Incredible views if you catch a sunset there.
If you don't swing north, you can go back into downtown and hit Westlake area or Chinatown. Right now I wouldn't suggest it given safety issues.
Even though Caphill is known for it's nightlife, I think it's most charming by day. The food, parks, stores, and people are way more fun. Most interesting food in Caphill right now; Malaysian spot called Kedai Makan. The line can be long and they're only doing takeout right now, but it's so good. For specific dish recommendations hit me up. Favorite sushi joint in Seattle is Gokan Sushi, right in the heart of Caphill (Gokan Dragon roll is life (sorry Dermot but I like eel too much)). Tacos Chukis is debatably the best tacos in town (no fish taco though). Rhein Haus has the best German food.
If you're not eating, Cal Anderson is fun. There's usually pick-up dodgeball that's super friendly, funky, and jovial. Very date-dependent. I'm a big fan of ballroom dancing so I love going to Palace Ballroom for some evening salsa/swing. They have beginner classes that I promise to be super fun and charming dates.
There's a ton of cool shops and drinks around. Big fan of the Elliot Bay Bookstore, I can spend hours browsing there and talking about books with a date. I like how every aisle could be a conversation starter.
Molly Moons is a classic PNW funky ice cream shop. If you want to be extra hip, Salt & Straw is even funkier and experimental but it's still hella good. Just be prepared going in. For lunchtime snacks/vibes, Bakery Nouveau is the best french bakery in town.
UDistrict, Lower Queen Anne, Greenlake, Old Ballard to come...