The ones I usually cite are already on here. 8 Miles High by The Yardbirds and Santeria by Sublime. The latter I really dig because it doesn't sound like a showing off of the guitar at all, the song would actually lack if it didn't have that little solo piece there.
Something is to be said for early Elvis as well, the solos on his stuff was really good and still holds up. I couldn't find a really great example on short notice though.