I play in a blues session band. Every session seems to be different. Sure you' ll play a lot of I-IV's. But some jams are more rock-orientated (Jimi Hendrix), others have more of a country or rock and roll vibe and somestimes we end up playing cajun stuff. Also when there are horns sitting in we play something funky so the horn-guy can do his Maceo Parker-thing or we play some jazzblues so the horn guy can do some Sonny Rollins.
Here a list of things that you're likely to encounter :
Songs that go from I to V like 'Bring it on home'
Songs that have the II walking up to the V as in most jump blues tunes.
BluesWaltzes; JazzWaltzes ('All Blues' by Miles Davis, famous bassline)
and CajunWaltzes like 'Wallflower' by Bob Dylan. Listen to that one it is really confusing.
JazzBlues with I-VI-II-V turnaround
Songs by Chuck Berry (Breaks, I-V changes etc...)
Songs by John Lee Hooker (random change of chords, just watch the guitarplayer/singer)
Jimi Hendrix songs
' I gotta Woman' by Ray Charles (fast moving chords and different chords during the solo)
'Cantloupe Island' by Herbie Hancock
'Glamour Girl' , ' Stormy Monday' by T-bone Walker (I-II-III-#II-II turnaround)
'Kansas City' Starts on the five chords, really cool to nail that in a jam.
' Love her with a feeling' by Freddie King (Starts with breaks)
'Same Old Blues' by Freddie King (chords)