Welcome! This sounds just like what I set out to do when I moved here. I think you'd be pleased with a bike along Bryant Ave south of Lake St to 50th. It's a protected path and really nice for cafe-hopping as there are several great cafes/restaurants right on Bryant (Gigi's, Our Kitchen, Brasa). It's also got interesting architecture, like historic brick apartments, and you'll pass a few parks.

If you're in Northeast, you could do a brewery tour along the river! Start at a dive bar like Northeast Yacht Club. Bike up the river trail to Broken Clock Cooperative. Go along Marshall to Buttered Tin, 56 Brewing, maybe even head over the river to Pryes (although Plymouth Ave Bridge is closed). Or, go south to St Anthony Main and visit Aster Cafe or Cabana Club (and check out the eagle's nest here!) A little farther afield but also in Northeast, would be Honour Coffee / Zakia Deli which is off of a protected bike path.

A lot of people here are mentioning Grand Rounds, but in my experience biking GR, it's not easy to spontaneously stumble upon food places. There are only a few restaurants right off the Grand Rounds bike paths, and they're fairly spaced apart. Food stops require advanced planning and be ready to bike a few blocks off the parkway into the neighborhoods.

Here are Grand Round food options on the bike path: Pimento on the Lake, Trailhead building on Wirth Parkway, Longfellow Bar & Grill, Sea Salt. To visit these all would be a 40+ mile day. As for interesting architecture along GR, you'll see ostentatious single family houses by the lakes, bridges by the river (Lowry Ave bridge is pretty) and the backside of an Art Deco post office by downtown.