Love your DS's list, aquinas. I'll have to see if my no-longer-quite-so-little wants to try some Roald Dahl. Our summer list so far:
- Waggit
- Guardians of Gahoole series
- Warriors (cat series, as well as associated dog (Survivors) and bear (Seekers) series)
- Pegasus series (The Flame of Olympus and following--kind of a Rick Riordan-alike, but enjoyed by my child)
- Redwall series
- The Familiars series (described as for fans of HP and Warriors--bingo!)
- The Call of the Wild

Other than The Call of the Wild, which appears to have been selected by DC on the basis of wolves, you might notice a pattern of fantasy-quest series, preferably with anthropomorphized animals.

I'll admit to having let DC read through all of the HP books at five or six. YMMV, of course, but they didn't seem to be too scary at the time, but that might be because DC heard them all read aloud first, by DC#1 (in a British accent, of course!).

As we're discussing this, I'm reminded of George MacDonald. Those might be appealing too -- The Light Princess, The Princess and the Goblin, etc.

...pronounced like the long vowel and first letter of the alphabet...