Hi Josh,
I've really never tied (although the last 6 months have definitely gotten my interest up), so I really have no idea if these are easy to tie or not. I think you might be on to something with terrestrials, though - a foam beetle might be super effective and seems like it might be pretty easy to tie (but this is just me speculating).
Trout:
Elk Hair Caddis
Stimulator
Hare's ear
Warmwater:
Green Damsel Nymph (I love this fly for bass)
Wooly bugger (might be cool to experiment with kreelex, as well as tail length for leech/lizard/minnow emulation)
Clouser minnow
The other thing that was all the rage about 5 years ago that might be really effective around here was the mop fly - they're just a nugget taken off one of those dust mops and lacquered to a hook, but the internet said they were really great. I would think they'd be ok for both trout and warmwater and instructions should be readily available online.
Have fun
- J