Wow. I've been called out as having tremendous experience! I guess that comes with age. 😁
Anyhoo, I'm not sure that I can provide anything more than what's been said already by @REI-JohnJ , @hikermor and @Philreedshikes . I mostly do day hikes, and try to go out nearly every weekend. I'm also the designated "outfitter" of our small hiking group, so I carry the first aid kit and other group supplies, along with my personal stuff,like rain gear, insulating layer, or whatever else seems warranted for that particular hike (traction aids, extra food and/or water, gloves, etc) Everyone else carries their own food and water, etc. My "go-to" pack for most of these day hikes is my Osprey Stratos 26 National Parks Edition, which was an REI exclusive. I also have a Traverse 35 which I got at a Garage Sale and use for those weekend long camping trips. Like the others have said, you really don;t want to over-pack (unless the specific trip conditions warrant it).
I don't worry about ultralight, but prefer the overall durability and the ventilation afforded by the suspended mesh back panels these 2 packs have. It's worth the extra weight to me. Another nice thing is that with the compression straps, these can be pulled in to secure your gear, with the added benefit of not looking overly big.
Hope that helps!
Get out there and enjoy!
one or more gifts or other benefits from the co-op.