What is the cheapest/easiest/quickest/best way to digitize thousands of paper photos? I realize these four parameters may be mutually exclusive.

Lay them all out in a straight line. Attach camera to rc car. Drive car past pics. Basically Google streets but for your pics XD /s

Lots of great suggestions here though.

Cheapest: NAPS2 and your flatbed scanner, or your phone camera

Easiest: See above

Quickest: NAPS2 and a document scanner

Best: A professional digitizing service

I think you have three choices that represent different mixtures of your ask.

1. Just scan them. Most phones have either a built in or app-available function to take the burdens out of scanning documents and photos. With thousands, you’d be talking about stretching it over a few weekends, maybe, but you could do it while watching tv or listening to an audiobook.
2. Scan and edit. You can buy a higher end scanner that would allow you to have more control over the quality of each scan. You could also use photo editing software to color correct or make whatever edits to the hopefully only dozens of photos you really care about, while leaving the option to do so open if you suddenly need that pic of Aunt May at the picnic.
3. Pay a pro to do it. You can find services that are all over the place in price and quality (basically because they’re centered around either option 1 or option 2). If you go with a higher end place, you’ll get people with a much higher skill set in scanning equipment and using photoshop then you. Lower end is basically lie the clerk at the UPS store that sends faxes. I’d recommend against sending any really important ones through the mail, though, so this again might be where you’d want to sub-select on the ones you really want done well and the others that you’d only mostly want to keep.

The easiest, quickest, and best way I found to scan thousands of photos was to purchase an Epson FastFoto scanner. You stick a whole stack of photos into it, it scans them one after the other amazingly quick, then you stick another stack in and keep going. I did this with boxes of old photos of every size, some of which I literally had to cut out of photo albums. There are options for scan quality and resolution. It helps tremendously to have your photos organized for how you’d like to store them, so for instance have your 1989 Grand Canyon photos together so that they can be named and numbered as they are scanned. It will even scan the back of the photos if you have writings or labels you want to preserve. This might not be the cheapest option, but its fits your other criteria perfectly.

Cheap. Fast. Reliable. Pick two.

If you aren't concerned about the paper originals getting wrecked you could use an automatic document feeder and scan up to like 50 at a time.

If you care more for quality then use the flatbed scanner on a printer or a dedicated document scanner. Some scanner apps on Linux let you scan multiple flatbed images, which is just a timer that waits a certain number of seconds before starting another scan. That should make things a little quicker, but most ways will have you spend hours to scan 1000 documents.

If they're in good condition, you can get scanners with document feeders and software that aligns the scanned photo. No idea on the cost though.

You can scan them yourself, and lots of scanner software lets you scan multiple photos at a time and then separate them in the software. However you do it is going to take time though.

Check around your local walmart/target/walgreens etc, that have those photo labs/booths. Some have proper bulk photo scanners publicly available, and will (or you can) pass your photos through one and spit out a CD for fairly cheap (sub-$10 last I checked, but years ago).

I've used Google photo scan to digitize quite a lot of photos. Definitely not the quickest but it's very easy and very cheap (free) and especially useful if you intend to use Google photos.

You'll probably have to scan them in yourself. Get a scanner and start scanning. Otherwise you'll have to pay someone else to do exactly that, which will cost more, but might be faster depending on how much time you're willing to invest.

Go to a library, some have scanners with feeders that will scan to a flash drive.

Woah thousands? I guess maybe see if you can get your hands on a large flatbed file scanner (hit up some thrift stores) and just scan a couple at a time and crop later

Digitizers / mini-scanners are cheap

I read that as digest and thought we were getting another no poop for three days post.