I'd suggest Haggard as a full symphonic band, with "Eppur si muove".
Septicflesh are using a lot of orchestra parts, you can try Titan, Communion and The Great Mass.
Dark Lunacy had a violin in Forget me Not and Devoid.
Fleshgod Apocalypse uses piano and various orchestration parts, I'd suggest listening to their Agony album.
Probably less symphonic than ...
You may want to check Edu Falaschi (ex-Angra) project called Almah. Their second album, Fragile Equality, has frequent parts of symphonic/orchestration keyboards with complex guitars riffs and progressive parts.
I also recommend you to check the Swedish Operatic Metal band Therion, most of their albums have complex orchestrations parts mixed with Power/...
When it comes to technical guitars one should definitely mention Rhapsody(now renamed to Rhapsody of Fire). Give Gargoyles, Angels Of Darkness a try. In their older albums Luca Turilli was playing the guitars and he is very talented guitar player. The band split in 2011 and now there are two bands - Rhapsody of Fire and Luca Turilli's Rhapsody.
You may also ...
I think you should check the one-man-band (from Behold the Arctopus) project Direwolf:
Fist in Fetus are also technical and symphonic.
Therion, Nightwish, are symphonic, not so technical. Same thing with Haggard, Septic Flesh and Fleshgod Apocalypse, they are trully symphonic and progressive, but I wouldn'...
Your own musical journey might not be as unusual as you assume. A recent study showed that teenagers tend to like the music that is most popular at that moment, whereas people's tastes get less mainstream as they age. So it's very possible to tell you what your peers were listening to 15 years ago, but much harder to give a definitive answer for who they ...
Direct Answer to Your Question:--
Try "A Glimpse Beyond" by Dan Mumm.
[Warning: Harsh, Noisy, and/or Disorienting Sound in the video link directly above.]
This artist has the advantage of being a professional guitar teacher with materials you can visit:--