You want suggestions, I'll give you, well, I'll give you my thoughts.
On my first solo trip, I stayed at the Carousel. It's really close to the main plaza entrance and that was nice. But it's a motel, meaning the corridors are outside. I was SO nervous for some reason, having just that flimsy door between sleeping-me and the world. I also had a weird happening that trip where the steam from my shower caused the smoke detector to go off (around midnight, the night of the Vegas Monte Carlo hotel fire), and I ended up having to have my room door open for a little while. Although no creeps came by, no Carousel personnel came by either, and it ended up making me feel even MORE alone and vulnerable.
Please note I've been traveling the country solo since I was 17, have had two quick solo trips to New Orleans and walked around only feeling nervous there once (b/c of college guys out in the early AM still drink from partying before), I drove cross country the long way by myself, etc etc...I'm not a nervous nellie when it comes to traveling solo.
HoJo is a proper hotel with inside corridors, and even though it's about 5 more minutes walking from Carousel, I would choose that in the future. The sidewalks, during park hours and an hour or so before and after, are filled with tourists and cast members (and the occasional homeless person sleeping on a bus bench), and I've felt VERY safe walking to and fro. (note I didn't get worried until I was in my room well after the parks were closed and the tourists were asleep)
I might even go as far afield as the convention center Hilton, filled with conventioneers, and take ART. nice hotel, inside corridors, lots of people around.
PPH and DLH are of course surrounded by tourists, and proper hotels (I'm leaving off GCH b/c you nixed it and I haven't stayed there). DLH you walk through DTD or take the monorail into Tomorrowland, and PPH you walk allll the way through DTD or go out the front entrance, cross to GCH and get to DTD or DCA through that hotel. So both are nice and safe (there is a crosswalk across 4 lanes of road with PPH) and filled with tourists and CMs.
So those are my thoughts!