Don’t think you can hire bikes up Grouse and by the time you got to the North Shore, sorted out a bike and hit the start of the first climb, you’d have to turn around and go home again!
If you’re a hiker/runner you could get the shuttle bus from Canada Place to the foot of the Grouse Grind, do the grind (1hr average hike up a steep wooded mountainside on a well maintained signed path, just check its open at the end of March) then take the skyride back down to get a shuttle bus back. If that’s your sort of thing then it would be the best 4-5 hours you could spend although not much time for the pub!
A lap of Stanley park is about 15km to/from Canada Place. That should be hikeable in 3 hours give or take, very scenic and would take you through the nicer parts of the centre of town, plus past a few pubs etc. if you were really efficient you could probably hire a bike in the same amount of time (there’s loads of touristy bike hire places that would rent you a basic beach cruiser types bike or possibly a racer).
All the bike paths that follow the waterfront have pubs and cafes so you could just pedal along stopping at your leisure.
My beer recommendation would definitely be Fat Tug, fairly common in the bars, about 7% and strong hoppy flavour. Granville Stuff is nice but not as