You are facing the same problem as I (we all) do. Just like you said most sites are made by and made for the more experienced fans. I had the privilege to start out in 1971. But the younger generation of fans are in trouble. There's one thing I can advice you. Register on www.elvisfind.com which is an Elvis search machine. That gives an overlook on most sites. It is at least a good way to start. Maybe I can help you on information about certain albums if you can tell me what you're specificly looking for.
I have tried to find downloadable Elvis album sleeves but I came short on that one. Most of the sites only contains bootleg sleeves or FTD releases. Also on this one I might be able to help you out by scanning my album sleeves. It will cost some time but at least it's something.
Just let me know what you need.