I would recommend
one of Archos's Gen 8 tablets, all of which automatically update to Android Froyo 2.2.1 over wifi. Loading photos is easy; you just connect the device with a USB cable, which makes it show up as an external hard drive, and then copy or drag whatever photos you want into whichever folder you want (if you want to keep things simple, make a folder called "Pictures" and put them all there).
The only caveat is that the built-in image viewing software sucks. Fortunately, there's a solution; download
Large Image Viewer from AppsLib (Android tablets can't access the market, which is restricted to phones) and set it to open images by default. It only does jpegs, but then again, if your photos aren't in jpg, you are doing something wrong.