This is a play that I almost never use that I would like to add to my arsenal of moves.

I have only check-raised the river 4 times in the past 30K hands, I'll go ahead and post all 4 of them to get the discussion started, but I hope this thread focuses more on general strategy than on my specific hands. All 4 times I had a pretty big hand if not the nuts. What are some good situations to check-raise the river with a very strong hand, and when should you consider a river check-raise bluff?

Hand #1 - I put villain on nothing much and was giving him a chance to bluff the river. He thought for a long time before calling with the straight.
PokerStars No-Limit Hold'em, $1.00 BB (6 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

SB ($77.05)
Hero ($155.90)
UTG ($33.55)
MP ($155.30)
CO ($116.75)
Button ($116.95)

Preflop: Hero is BB with A, 4.
UTG calls $1, MP calls $1, 2 folds, SB completes, Hero checks.

Flop: ($4) 6, 5, 2 (4 players)
SB checks, Hero bets $3, UTG folds, MP calls $3, SB folds.

Turn: ($10) 9 (2 players)
Hero checks, MP checks.

River: ($10) 7 (2 players)
Hero checks, MP bets $10, Hero raises to $35, MP calls $25.

Final Pot: $80

Hand #2 - This guy was a frequent floater, again I put him on nothing.
PokerStars No-Limit Hold'em, $1.00 BB (4 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

SB ($102.95)
BB ($38.15)
Hero ($100)
Button ($59.20)

Preflop: Hero is UTG with T, 9.
1 fold, Hero raises to $4, Button calls $4, 1 fold, Pedro_chips folds.
Hero bets $7, Button calls $7.
Hero checks, Button bets $5, Hero calls $5.
Hero checks, Button bets $15, Hero raises to $44, Button folds.

Final Pot: $91.50

Hand #3
PokerStars No-Limit Hold'em, $1.00 BB (6 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

CO ($51.30)
Button ($37)
SB ($45.45)
Hero ($218.55)
UTG ($40.60)
MP ($39)

Preflop: Hero is BB with K, 3.
2 folds, CO calls $1, Button calls $1, SB completes, Hero checks.

Flop: ($4) T, A, K (4 players)
SB checks, Hero bets $4, CO calls $4, Button folds, SB folds.

Turn: ($12) 8 (2 players)
Hero bets $6, CO raises to $16, Hero calls $10.

River: ($44) 8 (2 players)
Hero checks, CO bets $10, Hero raises to $36, CO calls $20.30 (All-In).

Final Pot: $110.30

Hand #4
PokerStars No-Limit Hold'em, $1.00 BB (5 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

MP ($53.40)
Button ($34.05)
SB ($112.65)
Hero ($107.75)
UTG ($104.95)

Preflop: Hero is BB with 7, 9.
1 fold, MP raises to $2, Button calls $2, 1 fold, Hero calls $1.

Flop: ($6.50) J, 6, 8 (3 players)
Hero bets $4, MP calls $4, Button folds.

Turn: ($14.50) 9 (2 players)
Hero bets $1, MP raises to $4, Hero calls $3.

River: ($22.50) 5 (2 players)
Hero checks, MP bets $6, Hero raises to $20, MP raises to $43, Hero calls $23.

Final Pot: $108.50