This year was my frist experience at solo trips. Last year I went to WDW with my Father, his wife and my brother....none of them are into theme parks or Disney like I am (42 yr old male). They would leave the parks at 2pm or so every day. I couldn't believe they went to the trouble to go but didn't stay to enjoy the parks. I of course stayed (I also klept their park tickets to get extra fast passes...which was a perk).
After that I felt like I was on my own anyway and decided it is OK to go it alone. I went back to WDW this year in March to ride Everest and I went to DL in June to see the 50th decorations again before they went away. I stayed at the Best Western Anaheim Inn across from the main entrance. I never felt unsafe at all. There were always other park guests around, walking to and from the park. While that hotel had a couple of downsides, it was comfortable, clean, close and cheap. (This was the first time not staying at one of the DL Resort hotels.) I would do it again in a minute.
Here is a list of single-ride lines:
Disneyland Single-Rider Lines
Splash Mountain-CM collecting FP's, go thru exit.
Soarin'-ask CM at the door. May decide to use FP.
Mulholland Madness-enter thru special gate.
Maliboomer-single rider line when busy.
GRR-when busy, ask CM, thru exit?
Screamin'-single rider thru wheelchair entrance, take elevator, get pass
As you can see, DCA has more of a selection, but knowing these allowed me to save my fast passes for other rides. I did forget Splash Mountain had a single-rider line, while I was there.
I also found that as a single, I could fit in crowds better for fireworks, parades, shows, etc, without having to wait as long because I wouldn't take up much space.
I also found the occasional fastpass on the ground and near the fastpass machines. This wouldn't help in a group, but a single fastpass for a ride works well with a single traveler. I was surprised at how often I would find these.
Good luck with your trip.