what is every one using for a go to pack for overnight adventures that include tent camping and having a sleeping pad and all the essentials to go for a day or more if wanted???
We have a Granite Gear Vapor Trail pack that we got from REI. This pack worked great for an overnight hike in campsite. This pack also works well for day hike too because it is easy to adjust its size.
That's a tough call as your pack size will be determined by a few things - starting with your sleep system and your tent. If you're carrying ultralight gear, then you may find a 40 L pack is ample in size. But if you're more like me, for example (not an ultralight guy), 40L is not enough.
I have the Gregory Baltoro 65 and I use that for all my backpacking - from a single overnight to... however long. But that's because it's extremely comfortable for me and holds my gear (with a bit of room to bring some luxury items if i wanted).
Best thing to do is to take your tent and sleeping bag into your local REI and have someone help you figure out the right size. If you don't have one near you, you can set up an online/virtual outfitting session and have someone help you size the right pack.
Backpacking packs generally require sizing and fitting to be comfortable so unless you have some experience it is best to get fitted at an outfitter like REI.
The most important measurement for a backpacking backpack is torso size which is hard to measure yourself
As @Dad_Aint_Hip suggests, the pack and the pack capacity you need depends on how bulky and heavy the gear you need to carry is. That generally depends on what you have now, your budget and your camping tolerences and preferences.
For an overnight or weekend a 50L pack works for many but if you are hoping to use gear you have for car camping you will probably find it too small.
I agree you must size it for your tent and supplies, but I will also tell you what has worked for me. I have been using the Osprey Farpoint 55 for quite a while, but we don't typically hike very far with the whole fam (5-10 miles total). Fits a 2 man tent, couple pads, some clothes, water, and food. This only works if other people in the group are also carrying around the same things in their packs as our kids don't carry much if any weight. There is no extra room for luxury items. Typically stay for a day or two.