This is a great question. As I have been building my repertoire it has struck me that so many songs contain the same little licks and some of them I learnt from quite easy songs.
Some songs I learnt early on that were not too difficult but great fun to play were Satisfaction by Rolling Stones and Day Tripper by the Beatles. I think learning these gave me a lot of confidence to tackle harder songs.
Day Tripper is a good example where the lead break is relatively straightforward but I learnt a little lick in there that I see in song after song.