By decreasing popularity :
Main line Caro-Kann
I believe this is the most played opening with both sides castling long.
[fen ""]
1. e4 c6 2. d4 d5 3. Nc3 dxe4 4. Nxe4 Bf5 5. Ng3 Bg6 6. h4 h6 7. h5 Bh7 8. Bd3 Bxd3 9. Qxd3 Nd7 10. Nf3 e6 11. Bf4 Qa5 12. Bd2 Qc7 13. O-O-O Ngf6 14. Kb1 O-O-O
Various move orders and sub-variations are possible.
Petroff defense, Nimzowitch variation
To avoid facing an attack on the kingside, Black more and more often castles long in the 5.Nc3 Petroff.
[fen ""]
1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4. Nf3 Nxe4 5. Nc3 Nxc3 6. dxc3 Be7 7. Be3 Nc6 {7...O-O was the main line} 8. Qd2 Be6 9. O-O-O Qd7 10. Kb1 O-O-O
You can find games of Caruana, Nepomniachtchi, Karjakin or Vachier-Lagrave in this line.
French, Burn Variation
An interesting line is the Burn Variation of the classical French:
[fen ""]
1. e4 e6 2. d4 d5 3. Nc3 Nf6 4. Bg5 dxe4 5. Nxe4 Be7 6. Bxf6 gxf6 7. Nf3 b6 8. Bd3 Bb7 9. Qe2 Nd7 10. O-O-O c6 11. Kb1 Qc7 12. c4 O-O-O
This line is sometimes associated with Morozevich.
Ruy Lopez, Exchange variation
In the Exchange Ruy Lopez with 5.d4, Black most often castle short but long castle is also seen quite regularly :
[fen ""]
1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Bxc6 dxc6 5. d4 exd4 6. Qxd4 Qxd4 7. Nxd4 Bc5 8. Be3 Nf6 9. f3 Bd7 {9...O-O is the main line} 10. Nd2 O-O-O 11. O-O-O
This also happens with 10.Nc3 instead of 10.Nd2.
Others
I think there are also some lines in the Sicilian with b3, but I have to check how often they are played. @cmgchess correctly mentionned some classical sicilians in comments. And there must be a few other opening lines with double long castle, which don't come to mind right now.