OSX El Capitan -- I need to clean out my startup disk. I tried uploading all 11,000 items in my iPhoto to iCloud but I can't because I need more storage there. Which makes more sense, paying for additional iCloud storage for iPhoto or doing something else?
I suggest you to pay the small fee to Apple. I don't think you'll need the larger tier. You'll enjoy all the benefits of the integrated library between Apple devices. Also if you rely on free service like google you have to deal with the fact that Google can scan your photos for marketing purpose, giving up your privacy. It's up to you.
You can use Google Photos. It has free unlimited storage, and also has an "uploader" application that you can leave running in background in your Mac computer.
It turned out that when my iPhoto migrated to the new Photos app, OSX created a huge file, 44GB, called MyPhotoLibrarybackup or something like that. I backed that up to my auxiliary hard drive and then deleted it from my laptop (moved it to Trash and emptied the Trash). Surprisingly, this freed up only about 5 gigs. Now the "other" category in my storage is enormous, and I can't figure out why.